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Slide holding for Scanning - Ohnar and Other Options

Started May 21, 2021 | Questions thread
OP Halina3000 Junior Member • Posts: 32
Re: 80mm f/4 enlarger lens - a compromise

I did a few more tests yesterday comparing light sources between the projector and the Solux lamp and also the positioning of the opal diffuser screen. For most of the tests the differences were very marginal and quite possibly down to the exposure not being completely identical rather than any real difference in quality or colour rendering.

The one result that was not marginal was the 50mm MD lens on the BPM bellows. Excusing the inability to capture the full 35mm frame I was expecting this to perform well. It didn't.

I found that when opened up to f1.7 for focussing with tethered live view there were horrible fringes around any hard boundaries between light and dark parts of the photo. These improved when stopped down to f8 for the actual capture but did not completely go away.

It occurred to me just before packing up that I have a skylight filter more or less permanently fitted to the lens. I repeated the test without this and the fringing was reduced but it was still bad at f1.7. The best capture still shows fringing when I zoom in and the overall sharpness suffers (perhaps as a result).

So far the 80mm Rodagon is doing better. From what I can gather it is a 6 element lens (at least the non 'P' version is... I cant find much specific about the 'P'). What that tells me about whether digitising slides to APS-C is within its 'comfort zone'... I have no idea. I have also found out that it has a 40.5mm filter thread on the front (not sure about the pitch just now) so it might be possible to make something to reverse mount it. I'm not sure that I understand the whole reverse mounting thing or whether that would be worthwhile with this lens.

I've ordered some extension rings to try with the 40mm Canon lens. At the moment I'm not very optimistic but they were not expensive.

Buying a used macro lens remains an option but I'm not in a hurry to buy the first worn out thing that I see.

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