Ad
Ad
Ad
Pages: [1]   Bottom of Page
Print
Author Topic: Tests of medium/large format digital lenses  (Read 4078 times)
torger
Sr. Member
****
Offline Offline

Posts: 1607


« on: February 28, 2012, 12:47:23 PM »
ReplyReply

If I want to find out performance of Schneider Digitar and Rodenstock Digaron lenses, is the only way to look at their own MTF charts?

I'm looking into moving to MF digital for my landscape work which for me requires a long term strategy. This means that I may start off with a second hand 22 megapixel back but say 6-7 years from now I may have upgraded to a second hand 60 mp back. Then I don't want to find out that the lenses I've invested in over the years don't perform well at that resolution. Perhaps I can no longer shift because corner performance becomes too poor.

For 35mm digital, there are some focal lengths that perform well and others that don't. If I only get the best performing lenses I simply don't get all FOVs I'd like to have in my camera bag. This is becoming a larger problem now when the DSLRs are approaching 40 megapixels. This have made me aware of that it is preferable to know what lenses that exists for a system and how they perform before starting to invest.

I now would like to find out what the limits are in the Schneider Digitar lens series, and compare them to the considerably more expensive Rodenstock Digaron. Perhaps some focal lengths are too poor in the Schneider series and is better to purchase a Rodenstock, and for others the other way around. And why does the 43mm Schneider cost €2400 and the 47mm Schneider €1500, does the latter perform much worse, or is it a much better buy, or is it just considerably more complicated to make a 43mm compared to 47?

All these types of questions are relatively easy to answer for 35mm digital by just going through all tests you find on the net. But for these lenses I don't really know what the best way to find out is... perhaps people just buy the most expensive they can afford and hope for the best?
« Last Edit: February 28, 2012, 12:49:05 PM by torger » Logged
Clyde RF
Newbie
*
Offline Offline

Posts: 34


« Reply #1 on: February 28, 2012, 02:18:31 PM »
ReplyReply

torger--You are several notches ahead of me in your photo landscape pursuits, but like you, I like to be thinking well ahead to avoid waste regarding associated future energy and financial considerations. I'm not far enough along to address the answering of this post, but I want to thank you for the useful contributions you have made with questions on this and other recent posts. For me and probably others, you seem to be collecting information relevant to the resolving of issues that have been hanging in the balance for us as well--so please keep up the momentum.

Regards, Clyde 
Logged
theguywitha645d
Sr. Member
****
Offline Offline

Posts: 970


« Reply #2 on: February 28, 2012, 02:30:38 PM »
ReplyReply

The GetDPI forum has a lot of images and tests with these lenses. I would go there.
Logged
Brian Hirschfeld
Sr. Member
****
Offline Offline

Posts: 821



WWW
« Reply #3 on: March 04, 2012, 04:15:50 PM »
ReplyReply

Once the weather starts getting a bit nicer, and its a bit more enjoyable to be outside (I live in New England), I plan to do some extensive and detailed tests of the PhaseOne / Mamiya lenses I own, since I have noticed that there aren't that many reviews of them, and probably more interest then people realize. Although not explicitly the focus of reviews, there are some lenses commented on on my website in other articles currently, http://www.brianhirschfeldphotography.com

Directly reviewed the Hasselblad 300mm f/4.5; http://brianhirschfeldphotography.com/2011/12/07/hasselblad-300mm-f4-5-hc-lens-review-2/

This addresses the PhaseOne SK 80mm f/2.8 LS D and the Mamiya 120mm f/4 Macro MF D; http://brianhirschfeldphotography.com/2012/01/14/phaseone-iq180-a-love-story/

There are also some very brief discussions of the Mamiya 210mm f/4, 55mm f/2.8, and 80mm f/2.8 (non LS versions) here http://brianhirschfeldphotography.com/category/mamiya/

« Last Edit: March 04, 2012, 04:19:16 PM by Brian Hirchfeld » Logged

www.brianhirschfeldphotography.com / www.flickr.com/brianhirschfeldphotography
---------------------------------------------------------------
Leica / Nikon / Hasselblad / Mamiya ~ Proud IQ180 owner
EricWHiss
Sr. Member
****
Offline Offline

Posts: 2451



WWW
« Reply #4 on: March 04, 2012, 04:50:04 PM »
ReplyReply

The biggest problem with lens reviews is that most really only show sharpness are totally based on opinion rather than quantitative.  It's funny how a person can post a shot of a cereal box or brick wall and say how sharp a lens is.  Brian, it seems that you wish to develop a blog with test reports and I hope you will test but also that you'll use a methodology such as Imatest software and charts or use even Bart's chart for sharpness.  Distortion and falloff are also useful as is what the bokeh looks like, if a lens can shoot into strong backlight, whether a lens performs better close up or at infinity, if it suffers from either longitudinal or axial chromatic aberration.  If its an autofocus lens how well does it perform.   And for medium format - how well can the lens be manually focused (some are much better than others).   Whatever you do, please do shoot walls and call it day.


Logged

Authorized Rolleiflex Dealer:
Find product information, download user manuals, or purchase online - Rolleiflex USA
Brian Hirschfeld
Sr. Member
****
Offline Offline

Posts: 821



WWW
« Reply #5 on: March 04, 2012, 04:57:31 PM »
ReplyReply

I will certainly attempt to do that. Is this the software you are referring to? http://www.imatest.com/products/software/master/

and also, would you suggest using their test charts?
Logged

www.brianhirschfeldphotography.com / www.flickr.com/brianhirschfeldphotography
---------------------------------------------------------------
Leica / Nikon / Hasselblad / Mamiya ~ Proud IQ180 owner
Christoph C. Feldhaim
Sr. Member
****
Offline Offline

Posts: 2509


There is no rule! No - wait ...


« Reply #6 on: March 04, 2012, 05:08:06 PM »
ReplyReply

When thinking lenses - forget MTF charts, forget numbers: Loan a lens and see it!

Not all lenses are made equal:
There are good and bad individual lenses in a line,
some manufacturers compute their MTF charts from construction data , others measure their real lenses.
There is MUCH more in the MTF charts than just numbers.
The course of the MTF curve is important too for the result of the rendering of the image as well, not only the numbers in it.

Either have someone you can trust or test it for yourself.
This can not be replaced by looking up data.

Cheers
~Chris
Logged

torger
Sr. Member
****
Offline Offline

Posts: 1607


« Reply #7 on: March 05, 2012, 01:39:07 AM »
ReplyReply

For landscape it is not that many parameters one needs to know. Resolution is king. Bokeh does not matter, and vignetting, contrast, etc most can be well compensated for in modern digital post-processing, except resolution. In this case even a (well-focused) brick wall shot does say quite much. It's hard to find those brick wall shots for large format digital though, especially with shift involved. LCC issues and vignetting (too dark = hard to focus) is important though, but much easier to find out without a thorough test.

Quality variations between lenses can be a problem, i e that the lens you get does not perform as well as in the test. In 35mm digital with current resolutions it is quite well controlled, there are variations but within reasonable intervals. With the higher resolution of medium format it may become a larger problem, I don't know.

Testing everything before buy is of course best but not really feasible unless living close to a dealer which lets you try things without a huge renting budget. My experience of approaching a pro dealer as an amateur with limited budget is that the service level is not that great, since they know that they will not make much money out of me, and I understand them - someone got to pay for the support.

To get large format digital from where I live, I'm probably best off ordering from abroad. Test after buy and send back if it is out of spec is something I do, but I'd prefer to know what lenses that exist and should perform well before I start investing in a system, or else I could end up with a situation that for certain focal lengths there are no good lenses at all, or the only good one costs €5000+ which is not a nice surprise to get.
« Last Edit: March 05, 2012, 04:20:24 AM by torger » Logged
ErikKaffehr
Sr. Member
****
Offline Offline

Posts: 8011


WWW
« Reply #8 on: March 05, 2012, 04:11:14 AM »
ReplyReply

Hi,

Imatest does have a cheaper and simpler version of the software called Imatest Studio. If you use Iamtest Master, I'd say that it may be a good idea to use it with their test charts, because you can make a complete characterisation of the lens with a single measurement (I believe).

Best regards
Erik

I will certainly attempt to do that. Is this the software you are referring to? http://www.imatest.com/products/software/master/

and also, would you suggest using their test charts?
Logged

dchew
Sr. Member
****
Offline Offline

Posts: 583



WWW
« Reply #9 on: March 05, 2012, 05:23:35 AM »
ReplyReply

torger,
You've mentioned not having a dealer near you.  One other source of info that you might try is another photographer near where you live.  Check the web, or find the company rep / importer.  Ask them who and where the pros are that are using the type of equipment you are interested in; you might be surprised how many there are.  I find most people are very willing to help, and would probably meet with you so you can get a bit of hands-on experience.  Obviously this will be qualitative info, but a real sit-down conversation with a user can be a valuable source of info.

It really is enlightening to read about the difference between two lenses, then try them side by side so you get real world experience to gauge what you read and put it into context.  Even if they are not the exact lenses you are interested in it can help.

I also second the value of the getDPI forum.  Good group of heavy users there, and there are many lens comparison discussions.

Dave
Logged

torger
Sr. Member
****
Offline Offline

Posts: 1607


« Reply #10 on: March 05, 2012, 07:42:42 AM »
ReplyReply

I also second the value of the getDPI forum.  Good group of heavy users there, and there are many lens comparison discussions.

Yep, I'm all over the forum and reading everything I can find, both on specific lenses and in combination with bodies and backs. The impression I have so far is that it is indeed possible to get these systems perform well, but that it is a rather high risk of some messup along the way, lenses, bodies or backs being off. So every part one buys needs to be tested thoroughly, see if it performs up to spec, and if not sent back for replacement / recalibration.

It seems like in the medium format tech cam world one really have to be one's own "quality engineer" to make sure that what you get performs as it should. Many manufacturers involved in a combined modular system which needs 10 um precision to perform well, lots of things that can go wrong.

I guess one needs to be prepared to deal with the situation this poor chap has went trough http://forum.getdpi.com/forum/75653-post36.html
« Last Edit: March 05, 2012, 07:48:20 AM by torger » Logged
Guy Mancuso
Sr. Member
****
Offline Offline

Posts: 1123


WWW
« Reply #11 on: March 05, 2012, 09:25:48 AM »
ReplyReply

Well simple fact is the 35 XL and IQ 180 are not meant to work hand in hand. Just won't work effectively with the heavy magenta cast caused by the small micron of the 180. Much better match for the 180 is the Rodie 32 in that focal length. The 35 XL works fine on the IQ 160. So yes if you have a IQ 180 some lens back combinations simply will not work. I'm in the middle of a SK28XL and Rodie 28 review right now but waiting on a Center  Filter for the SK to finish it up and make a purchase decision for myself. The biggest area on concern is wide angles below 40mm and having a happy marriage between back and lens.
Logged

Gigi
Sr. Member
****
Offline Offline

Posts: 430


WWW
« Reply #12 on: March 05, 2012, 09:45:55 AM »
ReplyReply

Torger -

You are clearly approaching this in a careful and deliberate way (good). Hands on experience will help you make up your mind: there is nothing like holding one of these cameras, and using it, going through the sometimes complex sequence and seeing how you like it, or don't. No Internet research can replace that. In the end, its still tactile.

On the issue of shimming and alignment, there are two different strands to consider:

1) the actual alignment and focus of the camera to the back
2) your source of information and control over that.

The two are only somewhat related, much different than on a DSLR. For example, the alignment of the back to the lens plane is critical. They can get knocked out, that's why the change in camera profiles in the past 10 years: wooden field cameras were too flimsy, Hassy went to a closed system to have precise control over all the pieces, why Leica gave up the DMR and went to the S2 (internal control over the sensor and its alignment). Everyone recognizes the need to control of that alignment. Once its set, its usually stays in place. Setting it is typically by shimming. How to check? Tethering, live view, check the 100% focus, etc.

Part two of this is when you take your picture and exercise your control, that is, you focus, and believe it to be in focus. This is a very different matter, as what you think may be in focus may not. Some sort of calibration between what is real focus (per the camera) and what you think is in focus (what you see) is needed - the best way is live view, checking 100% on the screen or tethered computer. There are other ways, such as using a distance measurement and then adjusting the lens per helical settings  (a la Arca) . Lupe on GG is another (remember, the GG has to be in exactly the same plane as where the back is....). The validity of each these has to be checked against the reality of the lens:back setup.

Some MF cameras, such as the SLR Hy6, incorporate these adjustments by allowing for "focus adjustments" for each lens: first you calibrate the lens:camera:back (checking by tethering and live view) to achieve maximum sharpness. Then note your settings for each lens. When  that lens is mounted, you dial in that adjustment on the camera. Pretty neat, yes? This is combining adjustment for each lens, its mounting (the first part of the puzzle), as well as incorporating any necessary adjustment of focus screen (or focus confirmation) to the back (second part of the puzzle). Sounds complicated, but is really not.

In short, both parts have to be confirmed: First get the lens:back right. Then calibrate your control so when you think you are in focus, you really are.

Logged

Geoff
ErikKaffehr
Sr. Member
****
Offline Offline

Posts: 8011


WWW
« Reply #13 on: March 05, 2012, 11:16:14 PM »
ReplyReply

Hi,

These articles may be of some interest:

http://www.josephholmes.com/news-medformatprecision.html

http://www.josephholmes.com/news-sharpmediumformat.html

Unfortunately we have sample variations. Unfortunately there may also be a correlation between price and sample variations.

Sample variations are in no way unique to MF/LF, by the way: http://www.lensrentals.com/blog/2011/10/notes-on-lens-and-camera-variation
Best regards
Erik






Yep, I'm all over the forum and reading everything I can find, both on specific lenses and in combination with bodies and backs. The impression I have so far is that it is indeed possible to get these systems perform well, but that it is a rather high risk of some messup along the way, lenses, bodies or backs being off. So every part one buys needs to be tested thoroughly, see if it performs up to spec, and if not sent back for replacement / recalibration.

It seems like in the medium format tech cam world one really have to be one's own "quality engineer" to make sure that what you get performs as it should. Many manufacturers involved in a combined modular system which needs 10 um precision to perform well, lots of things that can go wrong.

I guess one needs to be prepared to deal with the situation this poor chap has went trough http://forum.getdpi.com/forum/75653-post36.html
Logged

ErikKaffehr
Sr. Member
****
Offline Offline

Posts: 8011


WWW
« Reply #14 on: March 05, 2012, 11:48:13 PM »
ReplyReply

Hi,

A bad read! Awfully sorry!

Regarding focus stop at infinity I would have expected that most lenses would focus past infinity, but I actually found that at least my main lens on APS-C actually has optimal focus for infinity at the infinity stop.

Another issue is that many problems will be reduced if the lens is stopped down to f/22, but that also cuts resolution, a lot.

Best regards
Erik


I guess one needs to be prepared to deal with the situation this poor chap has went trough http://forum.getdpi.com/forum/75653-post36.html
Logged

Alan W George
Newbie
*
Offline Offline

Posts: 46


WWW
« Reply #15 on: March 06, 2012, 06:09:39 PM »
ReplyReply

I guess one needs to be prepared to deal with the situation this poor chap has went trough http://forum.getdpi.com/forum/75653-post36.html

It gets worse...

http://forum.getdpi.com/forum/gear-fs-wtb/30457-iq180-phase-df-body-lenses-cambo-wrs-35xl-various-misc-mf-gear.html

I don't think his experiences are typical.
Logged
Pages: [1]   Top of Page
Print
Jump to:  

Ad
Ad
Ad