My JTAT Sigma SA Nikon Adapter review

[Hardy Steiner]

I received the JTAT Sigma SA Nikon Adapter about 3 weeks ago. It was all nicely packed, you even get a CD with instruction videos with it.

Once you figured out how to use the adapter, it's not such a complicated process, but it is definitely not as easy as using the M42 adapter.
The advantages:
1) It's definitely a well made adapter
2) It works
The disadvantages that I can see:

1) Changing lenses is not a quick process. So it's nothing you can just do while you are hiking somewhere in steep terrain. You definitely have to find a place to sit down and rest the camera on. You need both hands to mount the adapter and the lens while the camera has to sit somewhere stable facing up.

2) The lens is not locked in the adapter. It sits tight in it. That's not a problem as long as the lens is compact and the aperture ring runs smoothly. With my 180 2.8 ED lens I am a bit in a worry that if I wiggle the lens just a little bit it will come off. I tried to wiggle this lens at home and it actually came off, but it hasn't happened so far in the field. So special care has to be taken in this case. There is no problem at all with my 24mm 2.8 AIS lens as it is way smaller. I wish this adapter locked the lens properly, but I guess there was not enough space to fit this mechanism into the adapter.

Below some pics (nothing fancy, just for you to see that it's working):













I am quite happy with the 24mm lens so far. I got the 180mm one mainly because I found the Sigma 180mm just too big for my everyday use (and I don't really need the macro). The 180mm is a very nice lens as well, but I do find that it has more CA wide open than in example the Carl Zeiss Jena 180mm 2.8 Sonnar.

I'd like to hear other people's opinion on the adapter as well ...

--
Best regards,
Hardy
==================
Join the Sigma DP Macro Group on:
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On Flickr: http://www.flickr.com/photos/diddy
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http://steinerphotography.blogspot.com

 

[convert]

Thanks, I'm tempted. there are some nice old nikkors (& kirons) out there begging for a decent sensor.
--
Andy
Dalinean
convert

SigmaSD9, SD10, SD15

lenses

 

[Rodrigo Cunha]

How is the aperture lever controlled? Or is the lens always stopped down to the set aperture?

 

[3dreal]

member tc95 offers a conversion-set for 350 usd.

carl zeiss jena sonnar 180/2.8 (there are multiple versions, latest is MC(Multicoated) is bad when light is not from back.
--
http://www.stereopan.org

 

[lita]

I pretty much concur with most of your findings.

I also found you can wrongly mount the lens in the adapter, especially if you turn the lens clockwise into the adapter instead of turning the adapter clockwise into the mount.

Like Mr. Steiner, I sometimes found that the lens would not be secured into the adapter and by wiggling the lens, it would come off.

There are 3 indentations on the side of the adatper that faces the Sigma mount, each one interlocks with the Sigma lens locking pin. The first adapter indentation, once clicked with the Sigma locking pin, places the adapter in the right position to accept the lens. At this point you insert the lens in the adapter, and turning the adapter clockwise slightly -before the the next indentation clicks- the lens falls into place. Then you turn the adapter further clockwise until the second indentation clicks with the locking pin and if I stopped there and wiggled the lens, it would come off. Now, if I turned the adapter just a bit further, until the 3rd indentation clicked with the locking pin -and most of the times, I would barely hear the click sound if at all- then the lens would be better secured. I did not push the point much further though meaning trying to wiggle the lens at that 3rd position, but again it felt much more secure. I still wonder why there is a need for a 2nd indentation where the lens is not secured at all though.

A couple of times, since it became hard to reach the 3rd indentation, I did turn the lens (instead of the adapter) and I got into problems: the lens turned within the adapter way too far and sat skewed... not recommended.

Now, I have the gist of it, and feel more comfortable with the whole process.

After trying the adapter with a Nikkor 28mm AIS, on one side of the frame, my results were so poor, I decided to send the lens to Nikon and I am waiting for it to retest. I also tested a 50mm, a 60mm Macro and a Sigma 24-60mm F2.8 Nikon mount, and they did fine.

If you read this, Mr. Steiner, I just wanted to know if you had looked at the results with the 24mm AIS at 100% (pixel level) and found even results across the frame.

Thanks.

 

[Hardy Steiner]

Many thanks for sharing your thoughts on the adapter.

Yes, once the adapter is in the final position and I just wiggle the lens a bit, it comes easily off (at least the 180mm one). The problem is here that it is just a few millimeters for the lens to move before it can come off, whereas let's say on a M42 adapter its several full turns (so if a M42 lens gets a bit loose, it still doesn't fall off as it has a "longer way out").

In regards to the 24mm 2.8 AIS lens: From the few shots I've taken so far I am quite pleased with the lens. I haven't examined the pictures at 100% a lot, but whenever I did, the sharpness seemed to be quite good. By the way, this lens has a very long protruding rear tab/pin. This one can be easily removed though by just unscrewing the metal part it sits on. I expected this lens to work quite fine on a crop size camera, it will be interesting to see how it behaves on a full frame one. The contrast of the lens seems to be fairly decent as well. I had some other old 24mm lenses before and the contrast always seemed to be a problem (washed out colors).

Which 28mm lens do you have? Is it the Series E one or the AIS one? The 28mm AIS lens seems to have a very good reputation.

--
Best regards,
Hardy
==================
Join the Sigma DP Macro Group on:
http://www.flickr.com/groups/sigma_dp_macro/
My pictures on:
On Flickr: http://www.flickr.com/photos/diddy
On Mostphots: http://www.mostphotos.com/Diddy
http://steinerphotography.blogspot.com

 

[Hardy Steiner]

For the ones with aperture ring you can set it directly on the lens. I don't have any Nikon lens without aperture ring. There is a plastic insert which you can order as well for the latest Nikon lenses. I was told that you can then only set the aperture before you mount the lens ... but maybe somebody who actually used this plastic insert can clarify this.
--
Best regards,
Hardy
==================
Join the Sigma DP Macro Group on:
http://www.flickr.com/groups/sigma_dp_macro/
My pictures on:
On Flickr: http://www.flickr.com/photos/diddy
On Mostphots: http://www.mostphotos.com/Diddy
http://steinerphotography.blogspot.com

 

[DaSonyGuy]

Many thanks for sharing your thoughts on the adapter.

Yes, once the adapter is in the final position and I just wiggle the lens a bit, it comes easily off (at least the 180mm one). The problem is here that it is just a few millimeters for the lens to move before it can come off, whereas let's say on a M42 adapter its several full turns (so if a M42 lens gets a bit loose, it still doesn't fall off as it has a "longer way out").

In regards to the 24mm 2.8 AIS lens: From the few shots I've taken so far I am quite pleased with the lens. I haven't examined the pictures at 100% a lot, but whenever I did, the sharpness seemed to be quite good. By the way, this lens has a very long protruding rear tab/pin. This one can be easily removed though by just unscrewing the metal part it sits on. I expected this lens to work quite fine on a crop size camera, it will be interesting to see how it behaves on a full frame one. The contrast of the lens seems to be fairly decent as well. I had some other old 24mm lenses before and the contrast always seemed to be a problem (washed out colors).

Which 28mm lens do you have? Is it the Series E one or the AIS one? The 28mm AIS lens seems to have a very good reputation.

All E-series lenses are Ai-S versions too!..It simply refers to the version of Nikon mount they have (There are four diffrent versions of the Nikon F mount...pre Ai, Ai, Ai-S and Nikon AF) so a more correct description would be E series or non E series.

 

[Hardy Steiner]

Thanks for pointing this out!
--
Best regards,
Hardy
==================
Join the Sigma DP Macro Group on:
http://www.flickr.com/groups/sigma_dp_macro/
My pictures on:
On Flickr: http://www.flickr.com/photos/diddy
On Mostphots: http://www.mostphotos.com/Diddy
http://steinerphotography.blogspot.com

 

[lita]

Thanks for your further clarification about the adapter/lens combo being set in the final position and the lens being still capable of coming off. I am happy I did not push the point too far and definitely won't.

My Nikkor 28mm AIS F2.8 is not the E version. It is the other more expensive one, the one that received so many glowing reviews in the past, and has what Nikon called then "CRC": Close Range Correction, which denotes the use of a so-called "floating" element or group of elements, that moves when focus is changed from far to near subjects in order to better correct for the latter. This feat of optical design was worthy of mention then.

I have been playing around with adapters and lenses designed for other mounts with the Canon EOS 5D for quite some time now and found out that the wider the lens, the more precise the adapter has to be. That is why I was interested in your experience with the Nikkor 24mm AIS: being wider than my own 28mm, your results indicate that the adapter, at least your sample, is of good quality and confirm my feeling that my sample of the 28mm had to be sent back for re-alignment (the "re" in "re-alignment" is optional, of course: the lens might not have been properly aligned at the manufacturing stage). Obviously, my sample of the Jtat could be slightly off, but for some reason, it is not my feeling.

On another note, as I said in my previous post, I have tested the Jtat on a few other Nikon or Nikon mount lenses and, for comparison purposes, I used a Sigma DC 18-50mm F2.8 EX MACRO (which I had gotten just before the release of the similar 17-50mm F2.8 OS, therefore, at the time, the latest model). Now there is only so much you can gather from the results of a test (I have to say the subject I chose is rather pedestrian, to be kind) when it comes to the more subjective part of the assessment, but I have to say that both the general rendition and the sharpness of the pictures from the Sigma zoom quite surprised me when put against the corresponding pictures from the Nikon lens. I think my sample of the 18-50mm F2.8 is quite good (it did go to Sigma for alignment, though, and there is no need for the "re" in this case). Now, using Nikon lenses on an SD14, I am after something more than just sharpness and resolution, something that is a bit hard to describe but I could venture a word like "presence", if you get my meaning. I have yet to make a comparison with "less pedestrian" subjects. My working life does not leave me inordinate amounts of time for this kind of amusement, I have to say. In any event, you may have the time and opportunity to do just that, compare a Sigma lens to a Nikon lens of a similar focal length, and if that is the case, your impressions (as subjective as they may be) would make great reading.

PS Yes, I also do wonder what gives us the right to poke fun at these poor "pedestrians". Actually, I am quite the pedestrian, personally. : )

 

[Hardy Steiner]

It's good to hear that you were a bit surprised by how well the Sigma zoom actually fared. Technology has moved on quite a bit on since the Nikon lenses we spoke about were produced some 20 years or so ago. It seems like that wide angle lenses show probably most improvement (sharpness, contrast, etc). How easy is it to find a good 135mm m42 lens and how difficult a good 24mm or even 20mm one?

I just got a second hand Sigma Super Wide 24mm 2.8 some days ago and only had a chance to use it once. The contrast seems to be quite good. Maybe I can put together a comparison with this one once I get a chance.

--
Best regards,
Hardy
==================
Join the Sigma DP Macro Group on:
http://www.flickr.com/groups/sigma_dp_macro/
My pictures on:
On Flickr: http://www.flickr.com/photos/diddy
On Mostphots: http://www.mostphotos.com/Diddy
http://steinerphotography.blogspot.com

 

[Hardy Steiner]

... and I am really curious to seem some pictures from your 28mm lens once you get it back from service.
--
Best regards,
Hardy
==================
Join the Sigma DP Macro Group on:
http://www.flickr.com/groups/sigma_dp_macro/
My pictures on:
On Flickr: http://www.flickr.com/photos/diddy
On Mostphots: http://www.mostphotos.com/Diddy
http://steinerphotography.blogspot.com

 

[DaSonyGuy]

Thanks for your further clarification about the adapter/lens combo being set in the final position and the lens being still capable of coming off. I am happy I did not push the point too far and definitely won't.

My Nikkor 28mm AIS F2.8 is not the E version. It is the other more expensive one, the one that received so many glowing reviews in the past, and has what Nikon called then "CRC": Close Range Correction, which denotes the use of a so-called "floating" element or group of elements, that moves when focus is changed from far to near subjects in order to better correct for the latter. This feat of optical design was worthy of mention then.

I have been playing around with adapters and lenses designed for other mounts with the Canon EOS 5D for quite some time now and found out that the wider the lens, the more precise the adapter has to be. That is why I was interested in your experience with the Nikkor 24mm AIS: being wider than my own 28mm, your results indicate that the adapter, at least your sample, is of good quality and confirm my feeling that my sample of the 28mm had to be sent back for re-alignment (the "re" in "re-alignment" is optional, of course: the lens might not have been properly aligned at the manufacturing stage). Obviously, my sample of the Jtat could be slightly off, but for some reason, it is not my feeling.

On another note, as I said in my previous post, I have tested the Jtat on a few other Nikon or Nikon mount lenses and, for comparison purposes, I used a Sigma DC 18-50mm F2.8 EX MACRO (which I had gotten just before the release of the similar 17-50mm F2.8 OS, therefore, at the time, the latest model). Now there is only so much you can gather from the results of a test (I have to say the subject I chose is rather pedestrian, to be kind) when it comes to the more subjective part of the assessment, but I have to say that both the general rendition and the sharpness of the pictures from the Sigma zoom quite surprised me when put against the corresponding pictures from the Nikon lens. I think my sample of the 18-50mm F2.8 is quite good (it did go to Sigma for alignment, though, and there is no need for the "re" in this case). Now, using Nikon lenses on an SD14, I am after something more than just sharpness and resolution, something that is a bit hard to describe but I could venture a word like "presence", if you get my meaning. I have yet to make a comparison with "less pedestrian" subjects. My working life does not leave me inordinate amounts of time for this kind of amusement, I have to say. In any event, you may have the time and opportunity to do just that, compare a Sigma lens to a Nikon lens of a similar focal length, and if that is the case, your impressions (as subjective as they may be) would make great reading.

How about comparing the Sigma 105mm f2.8 EX macro with the Nikon 105mm f2.5 Ai-S, but obviously not on macro subjects.