Thorlabs ITL200 VS Nikon 200/4 Ai-s: Real World Comparison

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Macro_Cosmos
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Thorlabs ITL200 VS Nikon 200/4 Ai-s: Real World Comparison

Post by Macro_Cosmos »

I finally got around to stacking the comparison shots. The Nikon here is not the macro version.

Photographic interest is a wing segment of a sunset moth.

My setup:
- Tried to keep lighting consistent. The tubes have different length, so lighting was not 100% the same.
- Nikon D810, ISO 100, 4s shutterspeed
- +75 sharpness to the final stacked exposure
- 50 exposures stacked in Zerene Stacker, Dmap
- 5um/step, Stackshot high precision mode

Some Q&As:
Q: How was the ITL200 mounted?
A: I use SM2 tubes from thorlabs

Q: Why was sharpness applied? Why was it stacked instead of single exposure?
A: That's the normal post processing I do. I am interested in the final result (the baked cake), rather than the single raws (the ingredients).

Q: Why butterfly scales?
A: To my experience, most people aren't interested in photos of resolution charts. If enough people want such a comparison, I'll do it.

Q: CA?
A: Inconclusive. CA was not tested due to above.

Related threads:
ITL200 introduction, samples, setup: http://www.photomacrography.net/forum/v ... hp?t=37474
Comparison by Rik:
http://www.photomacrography.net/forum/v ... 0&start=15

Updates:
-I flocked the canonical adapter, did literally nothing. I then realised that the adapter was designed to stop stray light. Useless effort.
- I flocked the SM2 tubes. It was simple, I rolled up a piece of flocking material, used tape to secure its shape, and simply inserted it into the tube.
- SM2>F adapter also flocked. The diameter of the adapter internally is 41mm. Stupid since the $30 BR2a has anti-reflective finish and this $94 adapter doesn't. They do the same thing.

Result:
No more stray light hitting the sensor causing contrast loss and muddiness.

The comparison:
Image

100% resolution can be found here:
https://farm1.staticflickr.com/916/2928 ... 20dd_o.jpg

Conclusion:
The ITL200 edges the 200/4 ais slightly in terms of resolution and sharpness. The edges are significantly worse. The 200/4 ais does not have great edges either.

The SM2 tubes are expensive and require flocking just like the cheap M42 stuff. Bummer.

Can't comment on chromatic aberration. If anyone is interested, I'll pull out my resolution chart (goes to 400lp/mm, should be enough) and do another comparison. Otherwise visit Rik's thread.

Discussion:
It's safe to say that in my case, the $1000 tube lens setup is as good as using a 200/4 ais with an adapter, which sums to $200. The extra money is not worth it for a tiny edge of sharpness in the centre.

The ITL200 stack is not perfect. There's various artefacts produced by Zerene Stacker which point to the need of a deeper stack.

I'm also still waiting for a shuttercable for my D7100. The ITL200 should be great for DX, or at least I hope it is. :roll:

Before and after flocking:

Before: (colours here a weird because I didn't bother fixing WB)
Image

After:
Image

The hotspots have been completely eliminated. I'll contact thorlabs and give them some advice based on this finding. I still think for such a price, I shouldn't have to go through all the trouble of flocking.

Macro_Cosmos
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Post by Macro_Cosmos »

ITL200:
ImageDMap: Thorlabs ITL200 by Macro Cosmos (DH), on Flickr

200/4 ais:
ImageDMap: Nikon 200mm f/4 Ai-s by Macro Cosmos (DH), on Flickr

Stuff about the setup in my flickr gallery:
https://www.flickr.com/photos/133023063 ... 024382851/

Full resolution:
ITL200:
https://farm2.staticflickr.com/1761/422 ... 55bf_o.jpg
200/4 ais:
https://farm1.staticflickr.com/845/4315 ... 6159_o.jpg

Further work:
Get DX comparison done
Get raynox stuff done
Find the "sweetspot" in the infinity space of the thorlabs ITL200. Maybe the result could be improved.

Any tips on how to proceed to find this sweetspot? I can't think of a better way other than wasting 1000 shutter actuations.

rjlittlefield
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Post by rjlittlefield »

Macro_Cosmos wrote:Find the "sweetspot" in the infinity space of the thorlabs ITL200. Maybe the result could be improved.

Any tips on how to proceed to find this sweetspot? I can't think of a better way other than wasting 1000 shutter actuations.
It seems like you could get a very good first indication by using Live View to precisely focus the corner, then take just one picture per setup for detailed inspection.

The center should not be affected by separation between objective and tube lens, except for possibly a very slight difference in glare due to reflections.

--Rik

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