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DIY Lens MTF Testing

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craig66 View Drop Down
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Post Options Post Options   Quote craig66 Quote  Post ReplyReply Direct Link To This Post Posted: 08 February 2014 at 10:11
Following on in the tradition of various test sites (and because I can do what I please), I'll categorise the numbers on the above charts as:

>3000 : Excellent
2500 - 3000: Very Good
2000 - 2500: Good
1500 - 2000: Just OK
1000 - 1500: Poor
500-1000: very poor
< 500: Terrible

This scale is relevant only to tests on APS-C 24 mp cameras.
 



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Moredsir View Drop Down
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Post Options Post Options   Quote Moredsir Quote  Post ReplyReply Direct Link To This Post Posted: 09 May 2014 at 03:01
Hi Craig, that's just what I am after. Any chance I could make use of the scripts?
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Post Options Post Options   Quote craig66 Quote  Post ReplyReply Direct Link To This Post Posted: 09 May 2014 at 03:59
Originally posted by Moredsir Moredsir wrote:

Hi Craig, that's just what I am after. Any chance I could make use of the scripts?


This little project is on the back burner for the moment as I was still somewhat uncertain about test charts. You do NEED quality professionally printed test charts.

The code and scripts are a bit cobbled together at the moment. I'll review matters over the weekend and send you a PM. It's all on Linux so if you are on Windows, you would have to at least rewrite the scripts as batch files and as far as I am concerned you would be mostly on your own as I spent most of my career avoiding Windows in favour of UNIX . My windows knowledge is err... limited. I'll also have to review the Java code for portability, though shouldn't be a big issue.

In the mean time you could get hold of MtfMapper and dcraw and whatever else is needed and just have a play around with the MtfMapper surface plots using a chart printed on any old ink jet printer. The absolute MTF figures won't be flattering but it will serve for familiarization purposes. You can probably get a professionally printed A1 test chart for $50 or so. It must be high quality - things like the cheap large canvas prints won't cut it.

Install inkscape for viewing and printing the SVG test charts. Using wide area metering if shooting the test charts. +1 EV is probably about right, but check your histogram.

The other use for MtfMapper is checking (and hence micro adjusting) AF. It's fairly easy and there is no requirement for a high quality test chart.
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Post Options Post Options   Quote Moredsir Quote  Post ReplyReply Direct Link To This Post Posted: 09 May 2014 at 08:50
Thanks Craig, I am familiar with Linux and have VMs with a couple of distros just for mucking around that could run it on. I have noob level programming skills, enough to modify scripts probably.

Don't go to too much trouble, just if it fits in with what you are doing anyway.
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Phil Wood View Drop Down
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Post Options Post Options   Quote Phil Wood Quote  Post ReplyReply Direct Link To This Post Posted: 16 April 2018 at 11:47
Thanks to all for this thread - as a result of it I have started to play with MTF Mapper which looks like being an excellent tool for simply comparing lenses. I am sure that my initial trials using an A4 'lensgrid' chart and a copy stand will not fit everyone's idea of precision testing - but one of my interests is in copying historical documents so I am very keen to see how my lenses perform in this sort of set up.

However, I would also like to see how they perform from further away - the copy stand is too short for the MFD of many lenses in my collection of old glass. My next step must be a larger test chart - I shall get some A3 prints and investigate my local print shop for larger sizes.

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Post Options Post Options   Quote Bob J Quote  Post ReplyReply Direct Link To This Post Posted: 16 April 2018 at 12:11
Originally posted by Phil Wood Phil Wood wrote:

one of my interests is in copying historical documents so I am very keen to see how my lenses perform in this sort of set up.


Visiting the National Archives at Kew?
 



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Post Options Post Options   Quote Phil Wood Quote  Post ReplyReply Direct Link To This Post Posted: 17 April 2018 at 13:21
Originally posted by Bob J Bob J wrote:

Originally posted by Phil Wood Phil Wood wrote:

one of my interests is in copying historical documents so I am very keen to see how my lenses perform in this sort of set up.


Visiting the National Archives at Kew?


I certainly spend time at Kew, easily the most photographer friendly archive I visit.

I have now tested a few lenses and am getting some surprising results - I fear I need to eradicate a few more variables from the set up before I will trust the results. The biggest surprise has been that an old Minolta 28-100 D (the silver plastic one) is out performing (by some margin) a modern Sony DT 18-55 SAM II and an earlier Sony DT 18-55 SAM at 50mm.
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Post Options Post Options   Quote QuietOC Quote  Post ReplyReply Direct Link To This Post Posted: 17 April 2018 at 13:46
Originally posted by Phil Wood Phil Wood wrote:

The biggest surprise has been that an old Minolta 28-100 D (the silver plastic one) is out performing (by some margin) a modern Sony DT 18-55 SAM II and an earlier Sony DT 18-55 SAM at 50mm.

Many of the Minolta normal zooms are quite good at 50 mm. I'll recommend the Minolta AF 50 F3.5 Macro if you want really clean corner-to-corner images.
A68 30M 35 50 60M 16-50 16-80 18-55 18-70 18-135 55-200 55-300
F3 LA-EA1 6.5 16 20 30 50 60 16-50 18-55 55-210
600si: 20 24 28 50 100M 135 24-85 24-105 35-70 35-105 35-200 70-210 75-300 100-300D
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Post Options Post Options   Quote Bob J Quote  Post ReplyReply Direct Link To This Post Posted: 17 April 2018 at 13:47
Originally posted by Phil Wood Phil Wood wrote:

I certainly spend time at Kew, easily the most photographer friendly archive I visit.


They are a good bunch. I worked there for about 18 months back in the early 90s when it was still the Public Record Office - working on the specification for a new document ordering system and the first instance of their 'Guide' being available electronically... My system will have been replaced at least twice since then.

I felt terribly lowbrow, as it seemed like even the cleaners had history degrees, while I was just the token techie.
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Post Options Post Options   Quote Phil Wood Quote  Post ReplyReply Direct Link To This Post Posted: 17 April 2018 at 18:24
Originally posted by QuietOC QuietOC wrote:

Originally posted by Phil Wood Phil Wood wrote:

The biggest surprise has been that an old Minolta 28-100 D (the silver plastic one) is out performing (by some margin) a modern Sony DT 18-55 SAM II and an earlier Sony DT 18-55 SAM at 50mm.

Many of the Minolta normal zooms are quite good at 50 mm. I'll recommend the Minolta AF 50 F3.5 Macro if you want really clean corner-to-corner images.


I'm a bit of a cheapskate - but I'll watch out for one on ebay. At present a Sony DT 30 Macro is my go to option (50mm can be a bit long on my APS-C bodies).

My dream is an A99II with a supersharp macro - to digitise the local paper for the WW1 years (my current research focus). Sadly I have neither!

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Post Options Post Options   Quote Phil Wood Quote  Post ReplyReply Direct Link To This Post Posted: 17 April 2018 at 18:26
Originally posted by Bob J Bob J wrote:

I felt terribly lowbrow, as it seemed like even the cleaners had history degrees, while I was just the token techie.


But could they speak SQL?
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Post Options Post Options   Quote Miranda F Quote  Post ReplyReply Direct Link To This Post Posted: 17 April 2018 at 22:32
Originally posted by Phil Wood Phil Wood wrote:

The biggest surprise has been that an old Minolta 28-100 D (the silver plastic one) is out performing (by some margin) a modern Sony DT 18-55 SAM II and an earlier Sony DT 18-55 SAM at 50mm.


I'm a little surprised at that. The ones I've tried have had quite poor corners anywhere near full aperture, but my Sony 18-55 is better. For best cheap sharpness at close-focus I would highly recommend the 35-70 F4 which is very good in close-up, where a lot of lenses go soft.
A900, A58, 5d, Dynax 4, 5, 60, 500si/600si/700si/800si, various Sony & Minolta lenses, several Tamrons, lots of MF primes and *far* too many old film cameras . . .
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Post Options Post Options   Quote Phil Wood Quote  Post ReplyReply Direct Link To This Post Posted: 19 April 2018 at 11:34
Originally posted by Miranda F Miranda F wrote:

Originally posted by Phil Wood Phil Wood wrote:

The biggest surprise has been that an old Minolta 28-100 D (the silver plastic one) is out performing (by some margin) a modern Sony DT 18-55 SAM II and an earlier Sony DT 18-55 SAM at 50mm.


I'm a little surprised at that. The ones I've tried have had quite poor corners anywhere near full aperture, but my Sony 18-55 is better. For best cheap sharpness at close-focus I would highly recommend the 35-70 F4 which is very good in close-up, where a lot of lenses go soft.


I have only scratched at the surface with my tests - and can see where there may be problems that may render comparisons between lenses tested at different times more than a little dubious. Notably I have tested in natural light (often obligatory when photographing historic documents) - but it must lead to inconsistencies in contrast. I shall try again with an LED ring flash (seems to me to be the easiest solution to hand).

I have tried a 35-70 f4, but it cannot focus (at f4) on the A4 target at 50mm and fill the frame. Obviously it can focus in macro, but then the lens is a 35mm. I chose to compare at 50mm because I have a 50mm prime to assess the various zooms against. I am finding that a few old zooms don't have the MFD to cope. Once I am happier with my test setup I shall try all my zooms capable of 50mm - perhaps a stepped down 35-70 f4 will outperform those that can focus wide open?
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Post Options Post Options   Quote Miranda F Quote  Post ReplyReply Direct Link To This Post Posted: 19 April 2018 at 19:34
The 35-70 works well with a TC or a close up filter
A900, A58, 5d, Dynax 4, 5, 60, 500si/600si/700si/800si, various Sony & Minolta lenses, several Tamrons, lots of MF primes and *far* too many old film cameras . . .
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