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Old 12-08-2019, 10:44 AM
JA
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New COMA Killer

Hi Folks,

I hope everyone is happy and well. For your interest I've put together a comparison of the various "standard" focal length lenses for full frame use. As you can imagine there are many possible entrants and so to keep things manageable I've opted for 8 lenses in the 35 to 50mm focal length range, from Zeiss, Sigma, Canon and Nikon.

Notably there are a few lenses that I didn't include, because the test is not yet available on Lenstip and/or there are limits to how much I can easily compose as windows on a double monitor layout and maintain good resolution. The focus here is on this focal length range for sharpness and low coma performance.

The contestants are:
  1. Carl Zeiss Distagon T* 35 mm f/1.4 ZE/ZF.2
  2. Carl Zeiss Milvus 50 mm f/1.4
  3. Carl Zeiss Otus 55 mm f/1.4 ZE/ZF.2
  4. Sigma A 35 mm f/1.4 DG HSM
  5. Sigma A 40 mm f/1.4 DG HSM
  6. Sigma A 50 mm f/1.4 DG HSM
  7. Canon EF 50 mm f/1.4 USM
  8. Nikon Nikkor AF-S 50 mm f/1.4G

I would have liked to also include the new Zeiss Milvus 35mm f/1.4 and new Nikkor Z standard lens for the Z6 and Z7 which is reputed to be an excellent performer for sharpness and coma along with one of the Sony normal lenses and a Samyang 35mm. There was either no data available or not enough space and/or these lenses were tested on a much higher resolution sensor, which will obviate the resolution MTF50 results comparison somewhat. As it stands the lenses included in the comparison were tested on either a Nikon D3x or Canon 5D MarkIII so the results are comparable.

If you have a double monitor or large format monitor open the image full screen, but even then it suffers from JPEG and forum compression.

Choose your new COMA killer !
Also look at the sharpness data (MTF50) with the lenses wide open. It is quite telling.

Best
JA
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Last edited by JA; 12-08-2019 at 10:55 AM.
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  #2  
Old 12-08-2019, 10:57 AM
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Atmos (Colin)
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Having tested a Zeiss Milvus 50mm f/1.4, wide open the stars at the extreme corners of a FF are worse than Lenstip shows (at least my copy is) but at the edge of an APS-C they’re utterly perfect.

Having seen images from a few Sigma Art 50mm and Zeiss Otus 55mm, the coma is a bit worse on the Sigma than Lenstip suggests at the extreme edges. I haven’t had a chance to do a side by side comparison but I’d say that at the EXTREME FF edges the Sigma shows less coma than the Milvus 50mm but the Milvus has better CA and better stars at APS-C distances.
The Otus 55mm however is just magnificent in every respect but you pay through the nose for it.
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Old 12-08-2019, 11:53 AM
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Only 1
Sigma Art 40 1.4
But its a monster lens

The only other is Sony GM 24 1.4
Also Sigma Art 28 1.4.

The Zeiss Loxia 21 2.8 for Sony E mount cameras has no coma wide open, but its F2.8. It also has superior coatings and gives deeper colour and more pleasing colour.

Greg

Last edited by gregbradley; 12-08-2019 at 07:54 PM.
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Old 12-08-2019, 06:11 PM
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Yeah the Sigma 40mm looks epic...
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Old 12-08-2019, 08:43 PM
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Quote:
Originally Posted by Camelopardalis View Post
Yeah the Sigma 40mm looks epic...
The main issue for it is the fact it weighs something like 1.2kgs and is really large. So it must be getting to the size that will make balancing the camera on a tracker more difficult and its weight possibly could even start causing tracking issues. Perhaps not, as a lot of trackers are quite tough.

Greg.
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Old 13-08-2019, 05:53 PM
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Balancing in rings sounds essential. I use a 1.6kg scope on my tracker and it works pretty well.
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Old 13-08-2019, 07:45 PM
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Very interesting, JA. I have the Zeiss Milvus 35, F1.4 and while it would not produce consistently round coma free stars at the edges until around F3.5/F4, the image brightness and MTF would certainly be up there with the very best. As for the Milvus 135mm F2, that is already brilliant by F 2.2/F2.8. Love it!
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Old 13-08-2019, 09:58 PM
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Quote:
Originally Posted by gregbradley View Post
The main issue for it is the fact it weighs something like 1.2kgs and is really large. So it must be getting to the size that will make balancing the camera on a tracker more difficult and its weight possibly could even start causing tracking issues. Perhaps not, as a lot of trackers are quite tough.

Greg.
For a 40mm lens it is a very very large chunk of glass. My Polarie handles it just fine, though and the results wide open are pretty tight - better than my Leitz 50mm Summicron in the corners.

Here's an hours worth on Crux with the Polarie, Sigma 40 and D810a
https://www.astrobin.com/420737/
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Old 14-08-2019, 06:58 AM
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Originally Posted by alocky View Post
For a 40mm lens it is a very very large chunk of glass. My Polarie handles it just fine, though and the results wide open are pretty tight - better than my Leitz 50mm Summicron in the corners.

Here's an hours worth on Crux with the Polarie, Sigma 40 and D810a
https://www.astrobin.com/420737/
Lovely shot Andrew. A bit of coma but that's about as good as it gets at F1.4.

The only other lens that may do better is the newish Sony 24 1.4 GM. Sony specifically stated that they were able to minimise corner aberrations for astro. But the supply of them seemed to stop for a while as a few quality control issues surfaced on the net. They are making them again now.

F1.4 though is perhaps not the best target for a lens as my Zeiss Loxia is pretty perfect at 21mm f2.8 and with a tracker you simply expose longer or do more subs to compensate for the slower F ratio.

I tarted my Polarie up. I got the counter weight from the Star Adventurer and the upgraded holder from Vixen so the polar scope can always see through the holder plus I put a wedge on it.

Greg.
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Old 14-08-2019, 07:26 AM
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Quote:
Originally Posted by alocky View Post
For a 40mm lens it is a very very large chunk of glass. My Polarie handles it just fine, though and the results wide open are pretty tight - better than my Leitz 50mm Summicron in the corners.

Here's an hours worth on Crux with the Polarie, Sigma 40 and D810a
https://www.astrobin.com/420737/
What was the FStop for this image?
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Old 14-08-2019, 07:40 AM
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Thanks Greg - itís only a few extra pixels per star, so Iím pretty satisfied with it. There is the new Nikon ĎNochtí 55mm, which is claimed to be coma free at f 0.97, but it sounds like they are only releasing it for their new z mount, and it will be 3-5K... so not really an option for me.
I also did a similar mod to my Polaris. The counterweight definitely increases the payload, but being able to fine tune the polar alignment after setting the camera up makes all the difference.
Cheers
Andrew.

Quote:
Originally Posted by gregbradley View Post
Lovely shot Andrew. A bit of coma but that's about as good as it gets at F1.4.

The only other lens that may do better is the newish Sony 24 1.4 GM. Sony specifically stated that they were able to minimise corner aberrations for astro. But the supply of them seemed to stop for a while as a few quality control issues surfaced on the net. They are making them again now.

F1.4 though is perhaps not the best target for a lens as my Zeiss Loxia is pretty perfect at 21mm f2.8 and with a tracker you simply expose longer or do more subs to compensate for the slower F ratio.

I tarted my Polarie up. I got the counter weight from the Star Adventurer and the upgraded holder from Vixen so the polar scope can always see through the holder plus I put a wedge on it.

Greg.
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Old 14-08-2019, 07:56 AM
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Cracking shot Andrew

Are we in a golden age, optically, I wonder? So many fast lenses coming to market, we have f/2 scopes available, and good quality mainstream refractors at accessible prices
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Old 14-08-2019, 11:15 AM
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Cracking shot Andrew

Are we in a golden age, optically, I wonder? So many fast lenses coming to market, we have f/2 scopes available, and good quality mainstream refractors at accessible prices
Thanks Dunk! I wonder if weíre seeing improvements in optimisation of manufacturing and design from the industrial 4th revolution, or if itís natural evolution of the existing tech. Either way, we the consumer are the winner.
Cheers
Andrew.
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Old 15-08-2019, 06:59 PM
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What was the FStop for this image?
HI Colin - Wide open f1.4. I'll try and stick a corner comparison in here..
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Old 15-08-2019, 07:14 PM
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HI Colin - Wide open f1.4. I'll try and stick a corner comparison in here..
At F/1.4 that is spectacular!
I think you've just put another astro lens on my list
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Old 16-08-2019, 06:23 AM
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Originally Posted by JA View Post
.....
I would have liked to also include the new Zeiss Milvus 35mm f/1.4 and new Nikkor Z standard lens for the Z6 and Z7 which is reputed to be an excellent performer for sharpness and coma along with one of the Sony normal lenses and a Samyang 35mm.
That new lens is the Nikkor 35mm f/1.8 S for the new Nikon Z series mirrorless cameras. It is right up there with the sigma 40mm f/1.4. I did see a coma comparison of it versus the Zeiss and Sigma. I will post it later, once I refind it.

Best
JA
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Old 26-08-2019, 06:32 PM
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Sony seems to have kicked a goal with its 35 1.8 as well. I am not sure how it fares for corner aberrations with stars though.

Greg.
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Old 30-08-2019, 11:40 AM
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What about your Batis 25mm Greg?
I have one just recently, and the initial (and too early to comment absolutely) results are very favourable, even wide open.
Gary
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Old 30-08-2019, 01:37 PM
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What about your Batis 25mm Greg?
I have one just recently, and the initial (and too early to comment absolutely) results are very favourable, even wide open.
Gary
Batis 25 F2 is very good. Some corner distortions but not bad and they correct in Lightroom using the distortion slider.

The thing about the Batis 25 that seems superior to other lenses is colour transmission. I find images using it always seem more colourful than other lenses.

Greg.
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Old 30-08-2019, 02:35 PM
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Which makes me scratch my head when I see yours for sale? I read a DXO Mark "Greatest Lenses" blurb recently, and the 25/2 was up there, as was the 55/1.8.
Gary
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