Camera lenses

[gregbradley]

I have been researching lenses for my Nikon D800E lately and some of that may help with those wanting to use lens for astrophotography.

One big advantage of Nikon cameras is that they are all compatible with every lens Nikon has ever made. Nikon has made an enormous number of lenses.

Some of them that are quite old in design are still made today. Others are very cheap on the 2nd hand market despite beautiful metal bodies and super sharp performance.

Nikon AI and AIs lenses are often very cheap 2nd hand. Most of these are F2.8 or better.

For example the 105mm F2.5 AI is under $200 yet is rated as a 5 out of 5 at a lens review site and is considered a classic portrait lens that is ultra sharp wide open.

There are 20, 24, 28, 35mm F2.8 AI or AIS lenses 2nd hand that are under $400 each. A new Nikon latest model 24mm F1.4 is $2000+ so you get a lot of lens for the price.

180mm F2.8 ED is a well known classic Nikon lens that is good for astrophotography and is under $450 2nd hand.

Pentax 67 165mm F4 is very good and illuminates a large chipped ccd camera (16803).

Pentax 67 lenses have about 87mm of backfocus making them very handy for astro as you can put a focusing unit in between them and the camera and still achieve focus.

I thought I would pass the info on about the Nikon AI lenses.

You can use these on a Canon easily with a cheap under $20 adapter off Ebay. They'd be all manual focus but all lenses are anyway in astrophotography so that's no different.

What you want is a fast lens (F2.8 seems very workable) that is good wide open with good sharpness and minimal chromatic aberration.

SBIG and FLI and no doubt Apogee sell adapters for their cameras for Nikon lenses.

I have used Canon FD lenses for astro up to 200mm and they seemed good bang for your buck as well.

Greg.

[Kunama]

Thanks Greg, Good info.
I had the 180 F2.8 Ais MF and it certainly was one of the best lenses I have owned.
My current and longtime favourite lens is the AF-S 80-200 IFED F2.8
beautifully sharp zoom.

[Octane (Humayun)]

I can also vouch for the 180mm f/2.8ED lens. It's a stunner.

H

[Omaroo (Chris Malikoff)]

Yup, I have the 105mm f/2.5 and have loved it for decades. A great astro lens, I'm also now enjoying it on my OM-D.

[gbeal]

While agreeing with most that is written here, I'd add that not all camera lenses are suitable for astro use. Even those "rated" highly by daylight/terrestrial users. CA, coma, and field curvature are always blatantly obvious when a star-field is imaged, not so with a portrait or landscape.
Astro and CCD combine to bring out the worst in optics somehow.
Having said that I have had good results with the Pentax 67 series, and a few of the Leitz/Leica series. I know others have had great results with the Nikkors.
Gary

[gregbradley]

It would be a good thing if people can post which camera lens they have found to be good and on which camera.

I found Nikon 180mm F2.8 ED good on an SBIG STL. Canon FD 200 F2.8 and 85mm were good.
Pentax 67 165mm F2.8 and 300mm F4 is good. 55mm F4 not so good but OK stopped down to F5.6 and also
using 2x2 binning on the camera. Nikon 50mm F1.8G is really good. I have Canon 50mm F1.8 and it appears to be
identical in terrestial imaging so most likely also for astro.

I am wondering if the Nikon 14-24mm would be good on a 16803 CCD. I will get a Nikon adapter from FLI and start
using some of these nice Nikon lenses on it to see how it works out. I think that one should be awesome.

Greg.

Originally Posted by Kunama

Thanks Greg, Good info.
I had the 180 F2.8 Ais MF and it certainly was one of the best lenses I have owned.
My current and longtime favourite lens is the AF-S 80-200 IFED F2.8
beautifully sharp zoom.

Nice lens.

Originally Posted by Octane

I can also vouch for the 180mm f/2.8ED lens. It's a stunner.

H

I had that lens once. Very nice. I think I used it on the STL11 and it worked well.

Originally Posted by Omaroo

Yup, I have the 105mm f/2.5 and have loved it for decades. A great astro lens, I'm also now enjoying it on my OM-D.

I picked one of those up in great condition yesterday on Ebay for the princely sum of $240. A new 105 F2.8 with vibration reduction etc is about $1250. Optically though it is probably either identical or very similar to the $240 version which is considered a classic portrait lens.

Originally Posted by gbeal

While agreeing with most that is written here, I'd add that not all camera lenses are suitable for astro use. Even those "rated" highly by daylight/terrestrial users. CA, coma, and field curvature are always blatantly obvious when a star-field is imaged, not so with a portrait or landscape.
Astro and CCD combine to bring out the worst in optics somehow.
Having said that I have had good results with the Pentax 67 series, and a few of the Leitz/Leica series. I know others have had great results with the Nikkors.
Gary

That is true. How to find out which is best with astro imaging is difficult though. I think a few basic guidelines may help though. Longer focal lengths are less lilely to show bad chromatic aberration than shorter focal lengths.

Faster F ratio lenses are more likely to show chromatic aberrations and spherical aberrations than longer f ratios. For example Martin's recent image test with a Canon 85mm F1.2. This is a highly desirable camera lens with fabulous background blur and super fast but you can see the compromises an optical designer has to make when making fast lenses and it had bad chroma in astro images.

Nikon and Canon 50mm F1.8 is a safe bet.

Modern cameras have built in chromatic aberration correction either in the camera or in the supplied software so this is not considered as important in terrestial photography as it is in Astrophotography.

Mind you its not that hard either to correct blue/purple ringed
stars. Noel Carboni has a Photoshop action that works really well. So does selecting the stars in the image, widen by several pixels, feather by a few pixels and then play with selective colour mainly set to magenta and reducing magentas and increasing cyans.

Also stopping down the lens a stop or two usually helps with all the lens defects, coma, chromatic aberrations, distortions.

Greg.

[Ross G]

I also have found the Nikon 180mm F2.8 to be very good. It seems to have a flat field and the stars are ok even in the corners. It does show some CA but thanks to Greg's advice I can easily eliminate this.

I have also used a few old Olympus OM lenses and the results have been very good although only in Ha monochrome so far. The 50mm F1.4 and 135mm F2.8 have been the best performers. You can get them on ebay for very cheap prices.

A friend has made me an adapter to mount my Minolta/Sony lenses on to a QHY9 and QHY8L and I am testing these now.

My best results so far have been from an old Nikon E Series 100mm F2.8 lens. It is very small and light. The stars are points across the whole frame and it seems to show very little CA. This was an under $100 ebay bargain.

However, the absolute best quality widefield astro photos I have seen have come from a friend's Canon 200mm F2.8L lens on his original Canon 5D.

Ross.

[Rigel003 (Graeme)]

Greg, can you suggest a lens (preferably older and cheaper) with enough back focus that would work with the FLI CFW-2-7 and ML8300? I think none of my current canon lenses are suitable.

[gregbradley]

Originally Posted by Rigel003

Greg, can you suggest a lens (preferably older and cheaper) with enough back focus that would work with the FLI CFW-2-7 and ML8300? I think none of my current canon lenses are suitable.

Pentax 67 lenses. 165mm F2.8 is good, 55mm F4 shows a lot of coma wide open but works 2x2 binned, 300mm F4 (there is a 300mm F4 ED IF which is a super lens but its $1500-2000 and rare).

You'll need an adapter made up from a Pentax to Nikon adapter which Precise Parts then fixes to a FLI CFW fitting.

I use a FLI PDF focuser in between lens and filter wheel. As even though you can manually focus these, the pdf gets the exact focus which is hard to get exactly manually.

I did see table on a site once that listed backfocus distances of different lenses. Pentax 67 were around 87mm but there were a few others like that. I'll see if I can find that.

You also get a FLI Nikon filter that fits the CFW but that would mean manual focus or you setup a Robofocus, a bracket to mount it on and a belt that wraps around the focus ring of the lens and this takes up no backfocus.

I found a couple of tables of backfocus distance:

http://en.wikipedia.org/wiki/Flange_focal_distance

http://allphotolenses.com/articles/item/c_6.html
Greg.

[RobF (Rob)]

Good thread Greg. Would be good to hear from Bert and Marc on their exploits.

I've had very limited experience with a few Pentax k-mount lenses and found these have worked very well in general on both my QHY9 (with Peter Tan adaptor) and Canon 450D. In fact I've had a lot of un-anticipated fun using them on my kids as portrait lenses. 28mm f/2.8 for widefield and 200 f/4 for closer in. 100 f/2.8 and 50mm f/1.8 still untried, but have Barnard's loop in mind. As nice as Pentax 67 lenses are, the reality is they're getting up in price towards what you might pay for an ED80, and the extra illuminated field un-necessary for 8300 sensors (perfectly understandable if you have a larger sensor or are buying for future redundancy though). Marc put me on to Pentax lenses, and I believe he buys M42 threaded lenses.

It sounds like a similar story to Nikon - they've managed to keep the mounting systems essentially unchanged over the years, such that older prime lenses with excellent glass but no electronics are now available at a substantial discount (and as I mentioned earlier they have the spin-off benefit of being fun but totally manual on your DSLR for daytime use - often fast enough to allow high speed indoor portraits of fasting moving children). Canon "nifty 50" has been good on my DSLR but one corner shows some coma. I haven't had this issue with the Pentax lenses.

Still need to experiment with different f stops for the pentax lenses. I believe Bert used to leave his wide open and use coffee tins or some such thing to stop down and avoid diffraction spikes? I'm a little surprised we don't see more lens work posted here. Imaging at shorter FL's is often quite rewarding, less demanding, and even possible piggy-backed beside/on top of your main imaging rig.

Getting the right adaptors for lenses can be fiddley. Oh to have a lathe and know what you're doing!

[gregbradley]

Originally Posted by Rigel003

Greg, can you suggest a lens (preferably older and cheaper) with enough back focus that would work with the FLI CFW-2-7 and ML8300? I think none of my current canon lenses are suitable.

Your CFW is about 22mm thick and the sensor on the ML8300 is 22.2mm down from the face. So you need lenses with say 45mm backfocus when looking at those tables.

That would be most lenses. Canon FD lenses would need the EF mount adapter (available on Ebay) and then they should work, Nikon lenses, M42 mount basically lots of choice. It may come down to which adapter for the FLI is readily available. They have one for Nikon ($175- ouch) and probably for Canon as well. Precise Parts could make one too.

Of course anything Zeiss would be awesome and would be awesome for daytime imaging.

Greg.

[gregbradley]

I've had very limited experience with a few Pentax k-mount lenses and found these have worked very well in general on both my QHY9 (with Peter Tan adaptor) and Canon 450D. In fact I've had a lot of un-anticipated fun using them on my kids as portrait lenses. 28mm f/2.8 for widefield and 200 f/4 for closer in. 100 f/2.8 and 50mm f/1.8 still untried, but have Barnard's loop in mind. As nice as Pentax 67 lenses are, the reality is they're getting up in price towards what you might pay for an ED80, and the extra illuminated field un-necessary for 8300 sensors (perfectly understandable if you have a larger sensor or are buying for future redundancy though). Marc put me on to Pentax lenses, and I believe he buys M42 threaded lenses.


The electronics are useless anyway for nightscapes etc unless the new 6D can focus in the dark (maybe it can). Live view focusing or magnified eyepiece or Bahtinov mask are available.

Yes Pentax 67 is really needed only if you want to use a focuser between the camera and lens like a FLi PDF or Atlas. Pentx 645 may still have enough backfocus to work in that situation. Filter wheels are about 20 -22mm, sensor is 22.2 mm deep in body in FLI ML8300, a FLI PDF focuser is about 20mm thick. FLI adapters to connect are flush and sit inside the unit so they don't add much - perhaps 1-2mm to the total.

If using a DSLR then no problem there, just a cheap Ebay adapter to match the lens to your DSLR. There are lots of those on ebay.

Greg.

[bojan]

Older russian lenses (for Zenit cameras) are very good, and cheap.
http://www.iceinspace.com.au/forum/s...ht=Tair+11A=#9
(this is the sharpest lense (stopped down of course) I ever had (in corners there is a bit of coma, though).

Also, see here, older canon (FD) lenses are very good.
http://www.iceinspace.com.au/forum/s...50mm+f1.4+lens
http://www.iceinspace.com.au/forum/s...s+modification
http://www.iceinspace.com.au/forum/s...ht=canon+100mm
http://www.iceinspace.com.au/forum/s...ht=canon+300mm
(Internal element of 300mm was later cleaned successfully with vinegar - it is now "as new")

Some photos taken with 50mm and 100mm FD lenses are on the link below:
http://www.flickr.com/photos/72914767@N03/?saved=1