So I bought this on eBay and Robert O'Toole called to my attention that this was for a prism arrangement which I overlooked in my haste to buy it. However, I have been using it with no problems and it is plenty sharp in my mind just shooting flowers. The Schneider MTF's are identical to the non-prism version. Anyway, I am happy with it, second image is taken wide open.
FujiFilm GFX100S ,Schneider Xenon-Sapphire 88mm f/3.2 prism
1/60s f/4 iso100 120-stack at 1.75x mag
FujiFilm GFX100S ,Schneider Xenon-Sapphire 88mm f/3.2 prism
1/50s f3.2 iso100 120-stack at 1.95x mag
Delphinium
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Re: Delphinium
Certainly looks good at this scale!
"A BSP must be used with this lens as its thickness of 25 mm (BK7) is basis of the optical design."
As a practical matter, you might want to test other apertures to see if there's anything to be gained by stopping down a bit farther. Stopping down will quickly reduce whatever spherical aberration is being introduced by the lack of prism. On the other hand stopping down will also increase diffraction blur. I have no idea which would be the better tradeoff in your setup.
--Rik
I would naively assume that they are giving MTF's for each lens used as intended, with the prism in place for the prism lens. The document at https://www.stemmer-imaging.com/media/u ... 75X-BS.pdf notes thatbobfriedman wrote: ↑Sat Nov 19, 2022 3:17 pmThe Schneider MTF's are identical to the non-prism version.
"A BSP must be used with this lens as its thickness of 25 mm (BK7) is basis of the optical design."
As a practical matter, you might want to test other apertures to see if there's anything to be gained by stopping down a bit farther. Stopping down will quickly reduce whatever spherical aberration is being introduced by the lack of prism. On the other hand stopping down will also increase diffraction blur. I have no idea which would be the better tradeoff in your setup.
--Rik
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Re: Delphinium
I see.... I just read the pdf you quoted... well I have been getting quite good results so who knows.
Now I know I pressed buy too quickly.
There is a difference.. the lens I have has a filter thread 40.5mm.... the data sheet says none.
Now I know I pressed buy too quickly.
There is a difference.. the lens I have has a filter thread 40.5mm.... the data sheet says none.
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Re: Delphinium
I just looked up Schott N-BK 7 and the index of refraction is aprox 1.5 so I am sure you are right.. that those curves need the prism..
oh well.
oh well.
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Re: Delphinium
That seems like it would be pretty easy to replicate if needed. Looks like results are oerfectly fine without, at least at web resolution.
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Re: Delphinium
since this copy I have has the front threads... I wonder if the lens was a mis-marked reject. ??
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Re: Delphinium
Which data sheet is that?bobfriedman wrote: ↑Sat Nov 19, 2022 4:18 pmThere is a difference.. the lens I have has a filter thread 40.5mm.... the data sheet says none.
The one I referenced at https://www.stemmer-imaging.com/media/u ... 75X-BS.pdf shows "Filtergewinde (Filter thread) // M40.5x0.5" in the diagram at upper left of second page.
--Rik
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Re: Delphinium
I do like the data sheet you found and I have bookmarked it... clearly it does say filter thread 40.5mm...
The data sheet I was referring to https://schneiderkreuznach.com/applicat ... asheet.pdf just has the filter thread absent which I misinterpreted as none. Probably because the use requires the prism.
Oh well wrong again.
The data sheet I was referring to https://schneiderkreuznach.com/applicat ... asheet.pdf just has the filter thread absent which I misinterpreted as none. Probably because the use requires the prism.
Oh well wrong again.