Jonathan's blog

Whether or not they have an interest in astronomy, at some point most photographers are likely to take a picture of the Moon. There’s a lot more to astrophotography than you might think, so I’ll walk through this step-by-step guide on shooting the Moon.

Capturing the best source image

It’s important to capture the best raw image data that we can, which will make the whole process easier. In this guide, I am assuming that you have a DSLR with a removable lens. Most of the advice also applies to film SLRs and digital compact cameras though, so don’t worry if that’s what you have.

Equipment

The lens has a lot more to do with the picture than the camera. For shooting the Moon, I recommend you use a telescope or a telephoto lens. The longer the focal length, the better. For most people, this means using a 70-300mm zoom lens, although if you have a 500mm camera lens, or a telescope which can be anywhere from 700mm up to 2000mm, then you can use that. On most crop-sensor DSLRs, a focal length of about 1400mm will make the Moon fill the viewfinder.

Tokina 400mm f/5.6 on Canon 450D

If you want to get a bit more reach, you could use a teleconverter. This fits in between your lens and your camera, and effectively multiplies the focal length of your lens – at the cost of losing some of the light and sacrificing some sharpness and quality. Common teleconverter sizes are 1.4×, 2× and 3×.

Kenko Teleplus MC7 2x Teleconverter

At these long focal lengths, the tiniest vibration will make your picture blurry. A tripod is absolutely essential – the sturdier the better.

Always use a cable remote to trigger the shutter without touching the camera. All SLRs support these, but most compacts probably won’t. If you can’t use a cable remote, the self-timer is your second choice. Set the timer, carefully press the button, and hope that the vibrations have died down by the time the photo is taken!

Canon Remote Switch RS60-E3

If your camera has mirror lock-up, you should always use it. This means the first time you press the button, the mirror flips up and the viewfinder blacks out. Then you wait a few seconds for the vibrations to die down, and then press the button again to fire the shutter. Mirror movements are a common source of vibrations and are probably the biggest cause of blurry Moon photos.

Technique

Forget autofocus. If your camera has a manual focus option, use it. It will be more accurate, faster, and will prevent your camera from re-focusing on each shot you take. If your SLR offers live view, use that and magnify the view if possible. Once you’ve set the focus, leave it alone

The Moon is bright (brighter than you think) and it is set against a dark sky. This really confuses the camera’s auto exposure, so it’s best to use full manual mode (usually marked M on your camera dial). You’ll need to tinker with the settings, but if you set the ISO to 200 then some reasonable starting settings for the full Moon might be a shutter speed of 1/250 and an aperture of f/11. Take a few snapshots until you get an exposure that looks about right. The most common mistake is to overexpose the Moon. We often think of it as being white, but it should be grey in the camera.

Keep your shutter speed fast. If you let it get too long, you will start to get motion blur. Shoot at least as fast as 1/250.

Choose a middling value for your aperture. Most telephoto lenses have a maximum aperture of around f/5.6 at full zoom. Usually this gives poor image quality, so it helps to stop down a few stops. Usually f/8 or f/11 is OK. Much smaller than that, and you start to lose sharpness again due to diffraction. If you’re not sure where your lens’s sharpest aperture is, check some reviews. Failing that, a good rule of thumb is the the sharpest aperture is 2-3 stops down from the widest.

Feel free to set the ISO as high as you like. You may be aware that higher ISOs cause more noise in the picture – especially in low light conditions. This is absolutely true, but in this case it doesn’t matter. We will discuss effective noise reduction techniques for astrophotography later in this guide. If choosing ISO 1600 enables you to keep a fast shutter speed and to use the sharpest aperture, so be it. Don’t be disheartened by the grainy pictures that come out – these are not the end product.

For reasons that will become clear in a minute, once you’ve found the ideal focus and exposure, you’ll need to take a few near-identical pictures. The Moon will naturally drift across the viewfinder – this is fine. You might want to place the Moon in one corner of the viewfinder and repeatedly take photos until it reaches the other side. Anywhere between 3 and 10 pictures is fine – just don’t forget that when shooting repeatedly, you still need to give vibrations time to die down after each mirror lock-up.

This next picture shows how fast the Moon moves across the sky. These exposures were taken just three minutes apart each, using a 300mm lens. Even leaving time to fiddle with the mirror lock-up between each exposure, you ought to be able to shoot at least one picture a minute, which will give you quite a few pictures at the end of the session.

Moon moving across the sky

Post-processing

Now that you’ve taken a handful of source images, we need to work on them to bring the best out.

Stacking

Stacking means taking a set of similar images, shifting and rotating them so they line up, and adding them together. This has the effect of averaging out noise from your camera, and distortions from atmospheric turbulence. The best free piece of software for Windows is called RegiStax. Those using Linux might want to consider ALE.

I wrote about ALE on this very blog not so long ago, but if you need a helping hand with RegiStax then I recommend you read this RegiStax tutorial. For the mostpart, you just follow through the steps it gives you – but there are a lot of scary options.

No matter which program you decide to use, after stacking, you will end up with a single image file which will look like a slightly improved version of a single frame. Now we move on to post-process this image in a more conventional photo editor. If you have Adobe Photoshop and you are familiar with it, then use that. I prefer to use GIMP which is similar to Photoshop but also free. It runs on Windows, Mac or Linux.

Colour channels

If you are shooting the Moon, it is effectively black & white, so we can do a trick with colour channels to improve sharpness at the cost of converting the image to actual black & white. (This doesn’t work if you want to end up with a colour photograph, by the way. If you’re shooting colour images of planets or similar, skip this step). Open your stacked image in GIMP.

Go to the Colours menu, Components submenu and choose Decompose. Make sure colour model is set to RGB, uncheck “Decompose to layers” and press OK.

This will split your colour image into its red, green and blue components, each of which opens as a new monochrome image. Now you can close the original image to save confusion.

Examine the three monochrome images you’ve got. They should be similar, but subtly different. Which one is sharpest depends on how much light pollution there is in your area, what colour it is, how well your lens/telescope performs at different colours and a million other factors. Zoom into each picture at 100% (do this by pressing 1) and have a look at the craters for comparison. When you’ve chosen the sharpest image, close the other two.

Unsharp mask

One of the best techniques for sharpening a slightly blurry picture is to use an unsharp mask. I won’t go into the theory here, but the basis of a blur is that a tiny dot becomes a small circle. Unsharp masking studies the image, and tries to convert the small circles of blur back into dots.

For this to work, we need to estimate the radius of the blur. Zoom into your image as far as possible (1600%) so you can clearly see the individual pixels as squares. Find an area of high contrast – either the edge of the Moon, or the edge of a crater. The edge of a crater or the lit edge of the Moon should be a sharp, defined line, but you’ll see that it is actually a gradual change, a few pixels wide. Count the number of pixels that it takes to cross the boundary.

In this example the middle red line (roughly) shows where the true edge of the Moon is. The outer two lines approximately show where the blur extends to. The distance between the two outer lines is roughly 5 pixels in this example. Work out the equivalent number for your image, and remember it.

Go to the Filters menu, Enhance submenu, and choose Unsharp Mask. Set Radius to the number you found in the previous step. Amount is set to 0.5 by default but you can change this if you wish. Numbers between 0.5 and 1.0 seem to work best.

Scroll around in the preview window to look at interesting parts of the image. Repeatedly tick and untick the Preview box so you can see what effect the unsharp mask will have. When you’re happy, press OK.

Colour curves

The name is a bit misleading – colour curves don’t have anything to do with colour in this context. They are a good way of enhancing contrast, though. Bring up the curves window by going to the Colours menu and clicking on Curves. The default “curve” is actually a diagonal line.

Arrange the curves window and your image alongside each other so you can see both at the same time. Drag the shape of the curve into a gentle S-shape. The exact shape and amount of the curve depends on your needs, but have a look at the next two screenshots to see what effect the curve has had. Click on the images to view them larger and use the arrow keys to go back and forth. You can immediately see that the dark patches are darker and the pale patches are paler.

Saving

That’s it! You’ve now finished all the basic editing in this tutorial. Save your image, but make sure you do Save As and choose a different name, so you don’t overwrite your original.

Summary

This guide touches upon a few of the most common techniques in astrophotography. It is by no means the ultimate guide. If you’ve got any questions, extra tips or if you spot any mistakes in this guide, please comment and let me know. Also, I encourage you to post your Moon photos at the bottom of this page, share your work and show off what you’ve done.

Further reading

On this blog

• Lenses for astrophotography – a comparison
• Astrophotography and stacking software
• Long telephoto lenses
• Mirror lenses: worth it?

Elsewhere

• RegiStax tutorial
• How to Photograph the Moon and Planets with Your Digital Camera
• Digital SLR Astrophotography

I went out for a scout this afternoon to find some new places to take pictures. As well as finding good locations, I needed to know which lenses to bring next time. None of the stuff in this article is ground-breaking but I think it’s a useful rule of thumb (literally).

For now, let’s forget about lens focal lengths in millimetres and think of the angular field of view of a lens. Hold your arm out straight in front of you. You can judge the angular size of a distant object by comparing it against the angular size of different parts of your hand.

Image from http://chandra.harvard.edu/photo/scale.html

So when you get home, you’ve got a list of places and the field of view you need to take each photo. Now you can use this table to figure out which lens you’ll need to give you that coverage. I’ve rounded the focal lengths to the nearest commonly-found focal lengths for APS-C DSLRs, 35mm full-frame (D)SLRs, and medium format cameras.

So to give a real example, if you are out on your scouting walk, and you note that you can cover part of a landscape with the palm of your hand, you know the angle subtended by the landscape is 10° and that you’ll need a 135mm lens for your DSLR when you return.

I hope this is useful to someone – I’ll certainly be using it from now on.

1. Usually the diagonal angular value is given, but in this example I think it makes more sense to use the horizontal dimension.

Last year I wrote about the darkroom I had set up in my loft. Since then I’ve moved house, so I need to build the darkroom again. This time I have a windowless utility room on the ground floor, with running water and a worktop, so it’s already better than what I had before. Here’s how I’ve set it up.

Click for a larger version, and see below for a bit more explanation. Apologies for the poor quality of this picture – I used my phone as my DSLR is currently tied up in a laser lab at Bristol university’s chemistry department. Hopefully photos to follow!

1. Safelight. This is a very old Paterson safelight, emitting just a dim red glow. Note that this is only suitable for black & white paper – all films must still be handled in total darkness.
2. Liquid concentrates – Various Ilford products, (including Multigrade developer, Ilfostop and Ilfotol), Rollei Digibase C41 chemicals and a bottle of Agfa Viradon New sepia toner.
3. Powdered concentrates – At the moment, just Ilford Microphen. Usually I would choose to use ID-11, but someone gave me 15 litres  of Microphen powder, so who am I to complain!
4. Universal film tanks. These are Paterson tanks and can take 35mm, 120 or 127 film.
5. Graduates, or as most people call them, measuring cylinders. I don’t know why the photography word is different. I also have some funnels for getting stuff back into bottles and some measuring jugs.
6. B&W film chemistry, diluted and ready for use in processing black & white films.
7. Gloves. Developer is quite alkaline and can make your hands sore if you handle it too much. Wearing gloves also helps prevent getting fingerprints on the film.
8. Colour C41 film chemistry – in this case, Rollei Digibase C41. It is diluted and ready for use.
9. Paper squeegee for getting most of the water off finished prints.
10. Film squeegee for getting most of the water off processed negatives. Seems that most people are divided on squeegees for film – they avoid water drying marks, but can cause scratches. Always clean your squeegee!
11. Scissors for cutting film up.
12. Pop-up drying rack for hanging prints over the sink to drip dry.
13. Rinsing tray. This is a normal paper tray, but I made some holes at one end so water trickles in from the tap, over the prints, out of the holes and down the drain. It’s an effective way of washing prints and saves buying an expensive print washer.
14. Paper processing trays for developing, stopping and fixing prints. There are extra trays in the cupboard under the sink for occasions where I also want to tone prints. I also have other sizes.
15. Paper easel. This one is a Durst 8×10″ but there is plenty of room for a larger easel on the baseboard.
16. Dust blower for getting dust off negatives before printing from them. It’s a Giottos Rocket Blower, and works well.
17. Focus finder for inspecting the magnified grain in the negative before printing.
18. Warm water bath. C41 colour processing must be done at 38°C, so I fill this wallpaper pasting trough with warm water and place the bottles of chemicals and the film tanks in it.
19. Thermometers & pencils, also some stirring rods. The thermometers are used to check temperatures of chemicals (20°C for black & white, 38°C for colour). The pencils are essential for making notes about the prints I make, so I can make more copies the same way in the future.
20. Enlarger. Mine is an LPL C7700 medium format enlarger, and can make prints from negatives as large as 6×7cm. I have 50mm and 75mm lenses for 35mm and 120-format negatives.
21. Work light, because sometimes you need to see what you’re doing

Not pictured:

• A clock that ticks loudly so I can time things in the dark
• A room thermometer so I can estimate how warm the chemicals on the shelves might be without having to check.
• A place to hang films to dry. A 36-exposure film is about six feet long, and obviously won’t fit on my print drying rack above the sink!

Most of the photography-specific equipment was purchased either from FirstCall Photographic or second-hand from eBay. Most of the more generic fixtures and fittings were bought from Ikea or other DIY shops.

If you are a darkroom enthusiast, buy Ilford film, paper and chemistry! It might not be the cheapest brand but it’s probably the best and it’s good to support a British company. Too many traditional photographic companies have discontinued products, changed focus or shut down entirely. Support traditional photography, and buy more film!

I’m no stranger to medium format photography. I’ve owned a few box cameras, a basic folding camera, and a cheap TLR for a while. Last year I started to take it seriously by buying a Mamiya RB67 outfit. I’ve been using it mainly for landscape photography and perhaps inevitably, I ran into the need to have movements on the camera.

I don’t have a scanner or an enlarger capable of taking 5×4″ negatives, and with the added cost of the sheet film, it would be an expensive venture. So I decided to buy a medium format technical camera, aka field camera. After looking around, I settled on one of the Horseman cameras – 970, 980, 985, VH or VH-R.

Horseman 980

But this isn’t my life story, nor is it a review of the Horseman 980. This is supposed to be a few snippets of information that I have found out for myself about the 980, and have decided to publish here given the scarcity of information about the Horseman 6×9 technical cameras.

Mamiya RB67 backs

Compatibility with RB backs is an important factor for me, since I already have several Mamiya backs for my RB67. Information is hard to come by, but as far as I can gather…

I think this can be roughly summarised to say that the Horseman cameras with rotating backs can take Mamiya RB67 backs. The older ones can’t.

The baby Graflok mechanism is the same, but the older Horseman models have raised silver metal areas around the film gate that do not allow the Mamiya backs to get close enough to the camera body for the sliding Graflok blades to mate. To mount a Mamiya back on a Horseman 960, 970 or 980 you will need to modify the camera itself. I haven’t seen a later Horseman body to compare.

Horseman 980 film gate

Film counter

This note particularly concerns the older roll-film back (pictured) with a chrome knob advance rather than a lever – although I have no idea if the same also applies to the lever-advance backs.

Horseman old-style 6×9 back

When loading a new film, there is no painted or engraved mark to align with the arrow on the paper backing. Instead you have to wind the paper on until you see the arrow peeping through a hole in the pressure plate. At this point, you close the back and wind until number 1 appears on the film counter.

However, in my experience, this means the film is wound about 5cm too far before the first exposure, meaning the last exposure is cut off. Now that I’m aware of this, I’ll just advance a little less to begin with. After I’ve figured out the best way of doing this reliably, I’ll comment on this post.

Shutter release

These Horseman cameras do not take a standard cable release. The standard type of cable release found on 99% of (non-digital) cameras has a small screw thread on the tip of the cable, and screws into a socket somewhere on the camera or lens. There is no threaded socket on the Horseman lenses. Instead, there is a tube that the cable release sits in, with a screw clamp to hold the cable in place. Sounds OK, except the diameter of the tube is 6.5mm and almost all cable releases are too thin to be gripped by the clamp.

Horseman cable release socket

The Horseman cable releases seem extremely rare – I haven’t found one anywhere online. There is also an adapter that exists but is very rare. I’ve searched extensively and found them only occasionally supplied with lenses – never on their own. I’ve pinched this photo from an eBay auction, to illustrate what the adapter looks like. It’s the small chrome thing in the shutter release hole.

Lens with shutter release adapter

I’ve contacted the Analog Photography Users Group and a camera shop that sells Horseman accessories, but neither were able to offer any insights.

I have worked around this by taking a standard cable release and wrapping it in a few layers of electrical tape to fatten it up a bit, so it gets clamped in the Horseman shutter release. It works reliably enough for me, and even looks OK when mounted.

Modified cable release

Modified cable release in Horseman socket

I decided to have a quick count of the film I have in stock.

Film

It seems I have 37 rolls of 120-format film, and 10 rolls of 135 (35mm) format. That’s a total of 730 pictures, assuming I shoot the 120 film as 6×7 negatives with 10 frames per roll, and the 135 film with 36 frames per roll. That’s getting on for around £200 worth.

For comparison I’ve also included a tiny 8GB MicroSD card which would be able to hold about 3000 pictures from my DSLR.

In stock, I have:

• Ilford FP4 Plus (my favourite B&W film)
• Ilford HP5 Plus
• Kodak Ektar 100 (my favourite colour negative film)
• Fuji Pro 160 NS
• Ilford Pan 100
• Tudor 200 (embarrassingly cheap, but cheerful)

Film is fun, kids!

Processing black & white film at home is easy. You just need a changing bag to load the film into a tank in darkness, and the rest can be done in the bathroom with the light turned on. The chemicals for black & white are normally used at 20°C but can be used at room temperature if you compensate for the time. You could even pop the chemicals in the microwave for a few seconds.

Many amateur darkroom enthusiasts (until recently, me included) are wary about developing colour film with the C-41 process, on the assumption that it is difficult, confusing, expensive, or all three.

It is true that colour process has to be more accurately temperature-controlled, and that the development should be done at 38°C. Immediately, this conjures up images of having to buy an expensive electronic water bath, such as the Jobo CPE-2. These machines do help, and they do cost hundreds of pounds. However, they’re not necessary. The development usually takes only 3-4 minutes and the later stages do not have to be quite so accurately controlled. This means it’s possible to use a plain warm water bath.

It’s not too expensive or confusing, either. There are beginner’s kits such as the Rollei Digibase C-41 LT20 which include all of the chemicals you need, with instructions. I paid £25 for a kit that can do about 20 films. There are bigger kits which are better value too, and it’s possible to restock on the individual chemicals in future. I’m no expert on the C-41 process, so you should probably read up on C-41 chemistry yourself.

I bought a wallpaper pasting trough for £2 and made a cardboard lid with holes for my bottles and tank to stand in the water. I filled the trough with water at 50°C and stood the bottles and tank in the water to reach the right temperature. The temperature of the water bath fell rapidly at first, and then slowed down. After about 5 minutes the water bath was at about 40°C so I waited until the temperature fell to 38°C, checked the temperature of the developer as well as the water bath, and set the development process going. The thermometer still read 38°C after the development was up.

By the end of the entire process of developing, stopping, bleaching, fixing and stabilising, the temperature of the water bath had fallen to 35°C, but this is still within tolerances.

My message to photographers who are wary of processing colour film at home: don’t be. You have to be careful, but you don’t need any special equipment other than what you’ve already got for your black & white work.

Have fun!

Background

I’ve dabbled in infrared photography a few times, originally using Maco 820c. The results were varied and I didn’t shoot it often enough to get a good feel for it. More recently, I bought some Efke IR820. If you’re reading this post, you presumably know vaguely about the film already, so I won’t go on about it.

I decided to make a renewed attempt to understand how to expose the film reliably so I can start taking decent shots with it. I don’t have a proper light meter. If I can be bothered to carry my DSLR, it makes an excellent spot and average meter. If not, I use an iPhone app called Pocket Light Meter, which is surprisingly good.

There are various methods of metering for infrared film. The light meters in some SLRs can meter infrared accurately through the filter; unfortunately the one in my Canon AE-1 Program doesn’t. Some photographers work out an “effective ISO speed” for their combination of film and filter, and use this with an unfiltered light meter. Different forums recommend different effective speeds and it’s hard to compare filters. The only way to work out what’s best for you is to sacrifice a couple of rolls to trial and error.

Filters

I am using a generic 720nm filter, which is a little stronger than a Hoya R72. The most comparable branded filter is a Wratten #88A. Refer to this comparison of infrared filters if you need to work out which type you’ve got.

Using Efke IR820 with an #88A filter, I decided to start with a speed of roughly 1.5 ISO. If using my DSLR’s light meter, this means metering at 100 ISO and then adding 6 stops of exposure. If using my iPhone light meter, I can meter as low as 6 ISO and then add 2 stops. I bracketed my exposures by varying amounts, and recorded the exposure information, and the way I arrived at it.

Procedure

I decided not to “waste” the film by risking taking badly-exposed artistic shots, but instead to take technically interesting shots that included foliage, sky, clouds, concrete, water, and other materials as a learning exercise. Once I’ve learnt the right effective film speed and the right amount of compensation for my meter readings, it’ll be easy to go out and take well-exposed shots almost every time. Then I can focus on taking artistic photos for publication.

My procedure was like this:

• Take one frame without the IR filter, using the camera’s meter set to ISO100. This is to rule out development errors later on.
• With the filter on, take infrared photos using any method you like for metering. This might include using the camera’s meter, a handheld meter, intuition, the sunny-16 rule, or something else.
• Bracket the exposures by ±2 stops, so you have a choice of exposures to study later.
• Record what each exposure was of, the aperture, the shutter speed, and importantly, how you arrived at the exposure. I kept a table like the one below (and these examples are a selection of my actual data).
• After developing, and making sure the unfiltered exposure is correctly exposed and developed, I inspected each negative and decided which were under- or over-exposed, and which ones were OK. Then I have a handy reference of which metering methods gave the best results.

My results

From studying the data I gained from these 39 exposures, the best-exposed images were achieved with a handheld meter set to ISO6, and then adding 2 or occasionally 3 extra stops of exposure. This indicates that the effective film speed of Efke IR180 with an #88A filter is ISO1.5 – ISO0.75.

The reason that the exposure compensation varied between 2-3 stops is probably due to the makeup of the composition of each scene. Foliage comes out near-white in the infrared region, but is relatively dull in the visible spectrum. The handheld light meter wouldn’t take account of this, so scenes with a lot of foliage probably need +2 stops added. Scenes that include a lot of sky, which is rendered black in infrared, will probably need +3 stops.

To see all of my favourite shot from the roll, see my photo blog.

I love photography, and I have an interest in astrophysics and astronomy. It only makes sense to combine them, and have fun with astrophotography. But which equipment is best for the beginner without breaking the bank? Let’s explore the options.

Some interesting photographs can be captured using a wide-angle lens to view the whole sky, but here I am specifically talking about long, telescope-like lenses. There are three solutions that I have at my disposal:

• Meade 60AZ 700mm f/11 telescope, with T-mount adapter for 35mm SLR or DSLR
• Tamron 70-300mm f/4-5.6 telephoto lens, native mount on DSLR with 2× teleconverter to make it a 600mm f/11
• Tokina 400mm f/5.6 telephoto lens, native mount on 35mm SLR with adpater for DSLR and 2× teleconverter to make it a 800mm f/11

So the “zoomiest” lens is the Tokina but that isn’t the only factor. Which lens is sharpest? What about chromatic aberration? What about other things affecting practical use for astrophotography?

First let me say a few words about each lens (and offer my apologies for the quality of the photos of the lenses – as you can see, my DSLR is in each picture so I was using my phone).

Meade 60AZ

The Meade 60AZ is an inexpensive 700mm telescope. The front element is 60mm in diameter, making it an f/11.7. There’s no variable aperture. It has the usual 1.25″ eyepiece fitting, so it’s easy to get hold of an adapter to turn this into a T-mount fitting. Once you’ve got T-mount, well, Bob’s your uncle, and you can adapt T-mount to anything else – including 35mm and digital SLR cameras, such as my AE-1P, EOS 450D and EOS 300. I bought mine from a car boot sale for £15, and then paid about £20 for the adapter to mount the camera.

Meade 60AZ on Canon 450D

It has an optically simple design with few elements, so chromatic, comatic and spherical aberrations may not be so well corrected for. This isn’t important for viewing by eye with an eyepiece, but aberrations show up more significantly in photographs that can be studied. Technically it is not a telephoto lens, since it does not have a telephoto group, and is correctly known as a long-focus lens.

Being a telescope, it comes with its own tripod which is a little flimsy, but easily capable of taking the weight of a camera.

Tamron 70-300mm

The Tamron 70-300mm is an inexpensive autofocus SLR zoom lens, offering a maximum aperture at 300mm of f/5.6. It mounts natively to the Canon EF mount, for use with 35mm and digital SLR cameras, including my EOS 450D and EOS 300. The 13 elements are coated to reduce flare and correct for various aberrations. My sample was bundled with my 450D at Jessops, but it costs around £100 new at the time of writing. I bought a Kenko Teleplus teleconverter for £30, second hand.

Tamron 70-300mm on Canon 450D

Autofocus is practically useless for astrophotography since there isn’t enough available light. On this lens, the focus ring is quite sensitive, undamped, and hard to use accurately. This will count against it in practical use.

Using a 2× teleconverter will double the effective focal length to almost match the Meade telescope, at the cost of a couple of stops of light and some sharpness – but still faster than the telescope.

This lens does not come with a tripod mounting collar but should be used with one, since the fully-extended lens with teleconverter is quite heavy, and unstable when the tripod attaches to the camera.

Tokina 400mm

The Tokina 400mm is a fixed focal length prime lens, with a maximum aperture of f/5.6. With a 2× teleconverter this gives me the longest effective focal length at 800mm while still being faster than the Meade telescope. It’s a manual focus lens with a large and well-damped focus ring which actually makes it easier to use than its contemporary rival, the Tamron. I paid £50 for this lens, second hand, and the Super Paragon teleconverter was about a fiver, I think.

Tokina 400mm on Canon 450D

It mounts natively to Canon FD-mount manual focus cameras like my AE-1P, but will work with Canon EF-mount EOS cameras with an adapter, which I wrote about recently. This adapter has the effect of making the lens a bit zoomier. I haven’t exactly measured the amount, but it could make this 800mm lens produce an image like a 900mm. We shall see.

This lens also does not come with a tripod mounting collar but should be used with one for best effect, because it is long, metal and heavy. They sure don’t make lenses like they used to.

Sample images

This article is about astrophotography really, but taking test photos of the moon or other celestial objects means carrying equipment to a dark place. I’m not sure I can be bothered to carry these three heavy lenses and two tripods and other accessories out at night, so for now you’ll have to make do with these images of the chimney at Frenchay Hospital, which is about one mile away. This is a city, so the atmosphere is quite hazy.

These pictures were taken with a Canon EOS 450D. The main images are exactly as they came out of the camera – no editing. The second images are cropped around the top of the chimney to show fine detail.

Meade 60AZ

Meade 60AZ

It’s immediately obvious that the image from the Meade telescope suffers from very poor contrast and colour saturation. This is perhaps obvious given its inexpensive and crudely coated elements. It might be possible to improve the contrast by using filters and shooting in black & white, since colour isn’t always important in astrophotography.

In its defence, the sharpness is good and I’m frankly shocked at how small the chromatic aberration is, given that this is a cheap 2-element lens.

Tamron 70-300mm

Tamron 70-300mm

The Tamron 70-300mm, a modern multi-coated lens, has no such problems with colour and contrast. The colours are vibrant and bold. However, it suffers badly from chromatic aberration. We might expect this from a cheap zoom lens – the effect will be less prominent with a fixed focal length prime lens.

As before, it might be possible to reduce the effect of chromatic aberration by using a coloured filter and shooting in black & white.

Tokina 400mm

Tokina 400mm

It’s immediately obvious that the Tokina 400mm is the zoomiest lens, with its teleconverter and FD-EF converter to mount it on the 450D. The colours and contrast are good, especially for a lens manufactured in the 1970-1980s.

The effect of chromatic aberration is also extremely small, presumably because it is a fixed focal length prime lens. I think the overall image quality is best out of the three lenses tested here.

Summary

The Tokina 400mm definitely seems to be the most useful for astrophotography and lunar photography. It has the longest effective focal length, the best sharpness, the best chromatic aberration and reasonably good contrast. Its manual focus ring is easy to use

Don’t forget that these images aren’t the best that each lens can produce – they are the lowest common denominator of what each lens can do. With careful processing, the images could be sharpened and have their contrast boosted. For some subjects, it might be appropriate to stack the images. For certain images, coloured or other filters could be used to work around the effect of chromatic aberration and atmospheric haze.

In the past, I experimented with a catadioptic mirror lens but the results were not great. In theory, mirror lenses should be well suited to astrophotography, so perhaps I had a bad sample. I also wrote some thoughts on other types of long-focus lenses for general use, and some of it might be relevant to astrophotography.

That’s enough discussion of lenses. I’m now waiting for a clear summer’s night when I can go for a short drive out of the city and hopefully capture some great images of the moon, and maybe other things in the sky. I should probably read up on astronomy so I know what to point the camera at!

I wrote a while back about software to generate star trails from a series of images of the sky. They are pretty and a fun and interesting form of art, but I wanted to have a go at taking photos of the night sky as it actually appears: still, and without trails.

It’s pretty hard to achieve good photos with a consumer DSLR. You have to keep the shutter speed faster than 4-5 seconds, otherwise you start to see motion blur creeping in. This means you have to turn up the ISO sensitivity of your sensor, which in turn leads to noise. As soon as you start to examine these photos closely, the noise is so distracting and it ruins the picture.

There are some ways to alleviate this – buying a faster lens, or a lower noise, higher sensitivity sensor – but these will cost you money. Lots of money.

I’ve been playing with the concept of stacking – where you take multiple images and later combine them to remove the noise. “Adding” the photos is the easy bit, but the stars will have moved slightly in between each photo, so they will need to be aligned by rotation and translation.

Some crazy people have attempted to do this by hand in Photoshop, but I’m far too impatient for that. There are some apps for Windows (both commercial and free) that will automatically align and stack photos. However, I wasn’t able to get any of them to work reliably under Wine on Linux, so I set about finding a native Linux stacking app.

The best I found was ale, which is command-line only but very easy to use. Both Fedora and Ubuntu package ale by default. To use it with default settings, it’s just a case of doing this:

ale image1.jpg image2.jpg image3.jpg image4.jpg output.jpg

This picture of The Plough was taken using a Canon 450D with 50mm f/1.8 lens. I took 12 exposures at ISO1600, 1″, f/5.0 and stacked them with ale. On my PC, a Core 2 Quad 8200 with 8GB RAM, it took about 53 minutes to stack 12 photos.

The stars are very small so you will probably need to click to see the larger version. You’ll notice that the background is very dark as ale has removed sensor noise, cosmic ray strikes and light pollution (I’m shooting in a city).

The Plough

In 1987, Canon introduced their new autofocus-capable EF lens mount for their EOS series of cameras – including today’s digital SLRs. It was incompatible with the older manual focus FD lens mount. The flange focal distance of the newer EF lenses is slightly longer meaning that an adapter for mounting FD lenses on an EF body must contain an optic to allow infinity focusing. This immediately means the image quality will be affected by the adapter. But to what extent?

I bought a Kood adapter (although there are many, many brands available) to use my FD lenses on my EF-mount EOS 450D camera. For £15, I thought it would be a fun way of getting some extra use out of my FD lenses, even if the quality wasn’t great.

Kood FD-EF adapter

The competitors

I decided to do a side-by-side comparison of my Canon 50mm f/1.8 lenses – FD and EF mount respectively. I shot at ISO400, 1/60s, f/4 with flash. (Perhaps some other time I will think of this experiment when it’s not dark, and try it in daylight.) The camera was on a tripod.  I used autofocus and centre-weighted program exposure with the EF lens. I used the same shutter and aperture settings for the FD lens, and focused manually using live view, magnified to 10× in on the LCD.

Canon FD 50mm

Canon EF 50mm

Results

For a start, you might notice that the FD lens is slightly more zoomed-in than the EF lens. This is a side-effect of the correction optic to allow infinity focus. I’ll show both photos here, including 100% crops at 1024×768. Click the images to view them at this size. Other than cropping, no sharpening or any other editing has been done on these images.

EF lens	FD lens
EF lens	FD lens
EF lens (100% crop)	FD lens (100% crop)

I am honestly staggered by these results – the sharpness of the FD lens is much better than that of the EF lens. It’s possible that the autofocus didn’t do its job properly but it does prove that this third-party FD-EF mount adapter isn’t so terrible. I can only speak for mine – I’m sure there are terrible ones out there.

Pitfalls

There are some other things to be aware of though. Obviously the FD lenses don’t support autofocus, so you have to focus manually. This is no problem on a genuine manual focus SLR body, but autofocus SLRs lack the split-circle and microprisms on the focus screen, so it’s a lot harder to focus using the viewfinder. Using live view is a workaround, and it is also possible to swap out the focus screen for one with a split-circle, microprisms, or both.

While FD lenses do support an aperture controlled by an FD body, it won’t work using an adapter like this. You will need to take your meter reading using any appropriate method, and then set the aperture – this is stopped-down metering. The viewfinder will darken when the aperture is stopped down. This particular Kood adapter has a switch to flick between fully open and stopped down, which helps.

Summary

But if you are in the same position as me, with an EOS SLR and a load of FD lenses, I don’t think you’ll regret spending a few quid to be able to use them on your digital body. The quality, at least of this Kood adapter, is perfectly good – perhaps flawless.

Update

As promised, I have now added some outdoor photos taken from my window. I slightly cropped the zoomed-out version this time, to give a comparable field of view. I’ve taken a 100% crop of the unaltered original to test edge sharpness.

Both photos were taken at ISO100 and f/5.6, but the EF version was taken at 1/50 and the FD version at 1/40 as the darkness was coming in. Both are a little underexposed, I think, due to the pale sky. and the FD version is a little darker.

EF lens	FD lens
EF lens	FD lens
EF lens (100% crop)	FD lens (100% crop)

On this occasion, the autofocus seems to have got it spot-on and my manual focusing isn’t quite perfect. Image sharpness otherwise seems good, especially towards the edge of the photo where you might expect softness,  and I can’t see any chromatic aberration around the chimney.

The real test will probably be using this lens in strong sunlight – which I shall try to find the time to do at the weekend.