rupert_griffiths

<p>I have some expensive lenses and live in a very damp place. I'm scared of fungus, so I've adopted a home-made solution: when not in use, I keep the lenses in a sealed plastic box with an open container of desiccant. This is not silica gel, it's the serious stuff, so I imagine the relative humidity in there is close to zero. I tested it out by leaving a broccoli leaf in the box overnight, and was entirely dried out in the morning, ready to crumble to dust in my hand. I've got it arranged so there's no way the desiccant could contaminate the lenses. </p>

<p>I know this is probably overkill, but it's what I could find for cheap. My question is, could I be harming the lenses through keeping them too dry? I can't afford to lose them or have them damaged. </p>

<p>Many thanks for any insight!</p>

<p>Wow! Once again, thanks to Paul, Rob, and Michael (who posted since I last said thanks).</p>

<p>If the stats I've seen for the Mamiya 7 50mm and 43mm are true (120 lp/mm across the frame wide open), then that looks unbeatable. However, I understand that the leaf shutter is closed while the lens is not in the camera, and I don't know how easy it would be to make it permanently open or to remove it altogether. It would seem a real shame to do permanent damage to such a fantastic lens, and any major surgery could harm those finely tuned optics.</p>

<p>Other that that, I'm getting a strong impression that the consensus opinion is that the Zeiss/Hasselblad lenses really are superior to cheaper glass in general. A voice in the back of my head is saying "cognitive bias", but I'm inclined to be heavily swayed by the opinions of a significant number of people with wide-ranging experience.</p>

<p>Thanks again to all!</p>

<p>This is all very useful information.</p>

<p>I'd looked into the Zeiss Super Achromat for the long focal length candidate, but it is astonishingly expensive and clearly very rare; that means there's not a great deal of information available on its performance. Frankly, I've seen some opinions and testing stats on the Mamiya 300mm f/2.8 APO that make me question whether the Zeiss lens could conceivably offer much more, and the Japanese model is readily available at much more reasonable prices.<br>

I'm looking into the shorter Zeiss lenses with the greatest interest. I know that Zeiss makes superb optics, but I'm slightly concerned that I've heard that they are sometimes deliberately slightly under-corrected to improve the look of the bokeh; that might make for a great photography lens, but is not so good for scientific uses as a more straight-up design, potentially maybe a Japanese rather than European optical style.</p>

<p>The short lens is really the most important, so I'm particularly interested in the options that have come up in the 40-50mm range - the 38mm Distagon is maybe a little too extreme, but still very relevant. Here I've seen some amazing things about the Mamiya 7 lenses in 43mm and 50mm as well as the Schneider and Zeiss options mentioned here, but as that's a rangefinder camera I'm worried that the shutter might be a problem (thanks for setting me straight about SLR leaf shutters, Q.G. - thinking about it, that should have been obvious to me). I've seen tests putting their resolving power at 120lp/mm, which is enough for us to be getting full resolution performance from a Nikon D800E.</p>

<p>The reason why we need medium format lenses is that this is for a computer vision setup where the camera will be shifted automatically behind a fixed lens. That's also why we're happy with 645 but even happier with 6x6 or 6x7 - more shift distance. Really, we can correct for distortion in the software so that's a secondary concern; less just makes it easier for us. However, there's not much we can do in this setup if the resolving power is too low (there are possibilities with superresolution and subpixel shifting, but it's a lot better if we can get the most possible out of the glass before getting into complex algorithms like that).<br>

I've also just had a chat with my colleagues, and a bellows focus lens is an option if the performance makes it worthwhile. It'll make it slightly harder to calibrate the machine after installation, but that's a one-time hassle that we can put up with. The Mamiya 50mm ULD is an option on the table for us. <br>

One a sidenote - I am aware that every lens I've brought up has been by Mamiya. I don't know why that is, I honestly have no particular affiliation to the brand and I've never used any of their products. Maybe their lenses are indeed among the best (although I also note that none of you people who know more about it have mentioned them!), or maybe Mamiya users are more into posting impressive claims on the internet regarding the resolving power of their lenses...</p>

<p>Thanks again for the all the suggestions so far, and please feel free to add any more.</p>

<p>Hi,</p>

<p>I am not a medium format photographer (maybe thinking about taking it up, but that's for another time).<br>

However, right now I'm working on a scientific project for which we need to acquire the highest resolution medium format lenses available. They'll be mounted to DSLRs through adapters, so we can use any brand (or mix of brands) for which adapters are available. As I understand it, that rules out RZ67 lenses, for instance, with their bellows focusing and leaf shutters. Maybe a leaf shutter on its own could be jammed open or removed, but we do need to be able to adjust the focus and aperture (so no AF only lenses).<br>

What we are looking for is lenses with minimal distortion, ideally with wide apertures that still offer good performance, and - most of all, and to the exclusion of all else - outstanding resolution. After that, a larger image circle is better than smaller, but anything from 6x4.5 upwards is still good. <br>

We've already identified the Mamiya 645 300mm f/2.8 APO as an utterly fantastic lens to cover our needs for long focal lengths. Unless anyone can suggest anything better, we'll almost certainly be using that lens, with its 645 format and reported 70+lpmm across the field even close to wide open.<br>

That leaves a need for something in the medium focal length range (80mm to about 130mm) and a wide angle option (under 80mm). We may look for a 150 or 200mm lens too, but looking at the experimental setup the wide lens is probably going to get most use. <br>

In terms of price, cheap is always good, but we are not looking to economise on quality. </p>

<p>I'd be very grateful for any advice on the very sharpest MF lenses that might fit our needs.</p>