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RF accuracy chart
Old 03-04-2008   #1
LCT
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RF accuracy chart

For those interested, here's a little chart of the R-D1's rangefinder accuracy for lenses at full aperture, based upon the formula b' = (e * f^2) / (k * z) where b' is the effective base length of the rangefinder, e the visual acuity (0.0003 at approx. 1 arcmin), f the focal length, k the aperture and z the circle of confusion (0.020mm for APS-C).
The effective base length (EBL) of the RD-1's rangefinder is 38.2 mm without magnifier (38.2 mm mechanical base length * 1.00 VF magnification) and 49.66mm with the 1.3x Megaperls magnifier (38.2 mm mechanical base length * 1.30 VF magnification).

[IMG]http://*******.com/rv7w/RD1_RFaccur.gif[/IMG]
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Old 03-04-2008   #2
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Quote:
Originally Posted by LCT
For those interested, here's a little chart of the R-D1's rangefinder accuracy for lenses at full aperture, based upon the formula b' = (e * f^2) / (k * z) where b' is the effective base length of the rangefinder, e the visual acuity (0.0003 at approx. 1 arcmin), f the focal length, k the aperture and z the circle of confusion (0.020mm for APS-C).
The effective base length (EBL) of the RD-1's rangefinder is 38.2 mm without magnifier (38.2 mm mechanical base length * 1.00 VF magnification) and 49.66mm with the 1.3x Megaperls magnifier (38.2 mm mechanical base length * 1.30 VF magnification).

[IMG]http://*******.com/rv7w/RD1_RFaccur.gif[/IMG]
Great!! Any chance you can do this for the Bessa R too? )please(
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Old 03-04-2008   #3
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Quote:
Originally Posted by Roberto
Great!! Any chance you can do this for the Bessa R too? )please(
No problem if you give me:
- the mechanical base length of the rangefinder
- the magnification value of the viewfinder
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Old 03-04-2008   #4
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Thanks!
The Effective base lenght (from Cameraquest) is 25.16mm.
It has a magnification of .68 and the phisycal base lenght should be the same as R-D1 (in fact 38.2 *.65 = 25.976)

Rob.
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Old 03-04-2008   #5
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According to Cameraquest, the VF magnification of the Bessa R is .68x and the mechanical (or physical) baselength of its rangefinder is 37mm.
This gives an EBL (effective baselength) of 37*.68 = 25.16mm and leads roughly to the same results as those of the R-D1 due to compensation between a 1.5 times smaller EBL (25.16mm vs 39.2mm) and a 1.5 times larger circle of confusion (0.030mm vs 0.020mm).

[IMG]http://*******.com/rv7w/BessaR_RFaccur.gif[/IMG]
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Old 03-04-2008   #6
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Thanks a lot! Very appreciated
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Old 03-04-2008   #7
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Hey, this is great !

Very much confirms my experience !

Note that your Bessa R + magnifier numbers correspond to the Bessa R3
without magnifier

Roland.
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Old 03-04-2008   #8
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this is a very cute chart
good stuff
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Old 03-04-2008   #9
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LCT, Just went in and took some other cameras as well, using your formula.
Hope I did no mistake:

IMAGE REMOVED. UPDATED BELOW ...

Cheers,

Roland.

Last edited by ferider : 03-04-2008 at 11:16.
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Old 03-04-2008   #10
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Quote:
Originally Posted by ferider
LCT, Just went in and took some other cameras as well, using your formula.
Hope I did no mistake:


Cheers,

Roland.
Cool! What about M6/M7?
Rob.
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Old 03-04-2008   #11
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I believe that Roland calculated the results for the MP on the basis of it having a .72x finder. This means that the results for the M2, M7 (.72x) and the M6 (.72x) would be the same as those for the MP. (Correct me if I'm wrong Roland ).
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Old 03-04-2008   #12
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By the way, thanks for doing these calculations you guys.
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Old 03-04-2008   #13
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Roland,

Can you add in the 35/1.2 also?

Interesting about the 90/4 on the CL being red. Are you just pickier than Leica/Minolta?

Send me a copy of your excel sheet if you would please. Very cool.

Thanks.

B2 (;->
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Old 03-04-2008   #14
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Great stuff!

I have a question about the coc, I've seen .02 used for various FF M bodies and in the calculations above, only the RD1 is using .02, everything else, even the M8 is > .02. Where is the coc value coming from?

And if I can focus in some of the red areas, does that mean I have an invisible built-in magnifier, or am I just lucky??
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Old 03-04-2008   #15
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If anyone's interested, the RD-1 chart, in a simplified and more numerical version, is on my R-D1 website: http://www.richcutler.co.uk/r-d1/r-d1_05.htm

Ampguy, see here for choice of CoC: http://www.richcutler.co.uk/r-d1/r-d1_02.htm. And, yes, you're just lucky!

In practice, I find that if I'm printing on paper larger than A4 (= 10 inches to you Americans!), the 0.02 mm CoC is too large...
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Last edited by RichC : 03-04-2008 at 08:17.
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Old 03-04-2008   #16
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35mm and 40mm lenses are too wide to pose any problem as long as they won't have a f/0.5 aperture.
0.03mm is the usual CoC value for the so-called 'full frame' format (24*36mm). It is the value that is still used by lens makers and DoF calculators nowadays:
http://www.dofmaster.com/dofjs.html
Of course changing that value would change the results but i still retain it AFAIC for the simple reason that it works well for me.
Same for smaller formats which have the same fraction of the FF CoC value as that of the so-called 'crop factor'.
For instance, APS-C cameras like the R-D1 have a 1.5x crop factor, hence a CoC value of 0.03:1.5 = 0.02mm on the same basis.
Now being out of the accuracy range does not mean that all pictures will be out of focus. It is just a matter of hit rate.
For instance, the Noctilux is OK but is not easy to focus on the R-D1. On the other hand, 90/4 lenses are out (by very few) on the Leica CL but are still usable at full aperture with a lower success rate than at f/5.6 that's all. At least that is what i seem to recall to be honest as the last time i've used a CL was 20 years ago more or less. [IMG]http://*******.com/rv7w/oldie.gif[/IMG]
Ferider, i have not checked your whole chart above but it looks great at first glance indeed.
Edit: Rich, thanks for sharing your charts. Would you have the same in meters by chance? Also could you explain where your 0.018mm value for the R-D1's CoC comes from? Perhaps it is explained in your great site, if so forgive me please.

Last edited by LCT : 03-04-2008 at 09:25.
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Old 03-04-2008   #17
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This is fun. Here is an update with more cameras.

IMAGE REMOVED. UPDATED BELOW ...

Bill, LCT, send me your email adress (ferider at yahoo dot com) and I'll email you the spreadsheet.

Best,

Roland.

Last edited by ferider : 03-04-2008 at 11:15.
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Old 03-04-2008   #18
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Quote:
Originally Posted by ferider
This is fun.

Bill, LCT, send me your email adress (ferider at yahoo dot com) and I'll email you the spreadsheet.

Best,

Roland.
Fun + Spreadsheets. Roland, by chance are you an engineer?
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Old 03-04-2008   #19
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Quote:
Originally Posted by LCT
35mm and 40mm lenses are too wide to pose any problem as long as they won't have a f/0.5 aperture.
0.03mm is the usual CoC value for the so-called 'full frame' format (24*36mm). It is the value that is still used by lens makers and DoF calculators nowadays:
http://www.dofmaster.com/dofjs.html
Of course changing that value would change the results but i still retain it AFAIC for the simple reason that it works well for me.
Same for smaller formats which have the same fraction of the FF CoC value as that of the so-called 'crop factor'.
For instance, APS-C cameras like the R-D1 have a 1.5x crop factor, hence a CoC value of 0.03:1.5 = 0.02mm on the same basis.
Now being out of the accuracy range does not mean that all pictures will be out of focus. It is just a matter of hit rate.
For instance, the Noctilux is OK but is not easy to focus on the R-D1. On the other hand, 90/4 lenses are out (by very few) on the Leica CL but are still usable at full aperture with a lower success rate as at f/5.6 that's all. At least that is what i seem to recall to be honest as the last time i've used a CL was 20 years ago more or less. [IMG]http://*******.com/rv7w/oldie.gif[/IMG]
Ferider, i have not checked your whole chart above but it looks great at first glance indeed.
Nice work!

BTW, I still feel that digital (because of almost zero depth of the sensor) is even less forgiving than film, which has some thickness and when printed (or scanned) show more in focus, because the enlarger (scanner) lens has also some DoF...

When using the RD1s on hyperfocal (yes, although I have been using the M8 more and more, I sometimes still use the Epson...), at least one aperture difference is needed (if not two!) to get really allround sharp pictures on largish enlargements...

The good news is that 800 ISO is no problem and even 1600 ISO (in B&W) is very feasible, when 400 ISO was the norm in film (for me).
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Still an RF fan when it comes to "just because" photography (including film).

Using (at the moment):
Leica M8 (B&W) with 28/2 ASPH; CV 12/5.6, Zeiss 21/2.8, CV 35/1.2, CV 50/1.5, CV 75/2.5
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Mamiya 7 + 43 + 65 + 150
And a bunch of m43 lenses on the E-M1
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Old 03-04-2008   #20
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Thanks Rich and LCT, I understand the math you are doing, was just curious if you had any primary sources for the coc info. vs the web/tertiary sources you have cited.

I do have pre M8 Leica info. for use of .02x coc, will cite it when I'm at my book.

Also, from practical experience, I have a higher hit rate with the RD1s (new) at 75/1.4 and 2.0 which are *RED*, than with CLA'd M6 .72 with Noct 1, and CLA'd CL with 40/f2 which should be *OK* Maybe the Canadian 75's used .03 for coc??

Would be interesting to see if this table corresponds to other users experiences, I'd guess not, or who in their right mind would use a Bessa or CL??!!

Also, maybe mention distance of subject?? Did you know that all of these setups focused on infinity at a far away subject should be *GREEN*
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Last edited by ampguy : 03-04-2008 at 10:07.
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Old 03-04-2008   #21
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Quote:
Originally Posted by ampguy
...from practical experience, I have a higher hit rate with the RD1s (new) at 75/1.4 and 2.0 which are *RED*, than with CLA'd M6 .72 with Noct 1, and CLA'd CL with 40/f2 which should be *OK* Maybe the Canadian 75's used .03 for coc??...
Indeed it is not normal at all. At f/1.4 your 75 is way out of the accuracy range of the Epson. It is even very difficult to focus on the M8. Also, the .72x M6 has a longer EBL than the R-D1 (w/o magnifier) and the 40/2 should not have any problem with your CL at any aperture IMHO. Did you have the 40/2 cla'd as well?
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Old 03-04-2008   #22
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Quote:
Originally Posted by LCT
Indeed it is not normal at all. At f/1.4 your 75 is way out of the accuracy range of the Epson. It is even very difficult to focus on the M8. Also, the .72x M6 has a longer EBL than the R-D1 (w/o magnifier) and the 40/2 should not have any problem with your CL at any aperture IMHO. Did you have the 40/2 cla'd as well?
Ted, are you framing your subjects for the 75mm like you would with the 50mm? (i.e. farther away from your subjects with the 75mm)
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Old 03-04-2008   #23
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Not that I don't want an SP ....

I am keeping this chart updated as we add stuff ...


Last edited by ferider : 03-04-2008 at 12:51.
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Old 03-04-2008   #24
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Can you take the 135 up to 3.5 and 2.8 please?

Thanks.

B2 (;->
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Old 03-04-2008   #25
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I thought the rule of thumb was the EBL should be equal to or greater than the physical diaphragm opening for the aperture. Given that, one would need at least a 50mm EBL to focus the Noctilux. I wouldn't bet on reliably focusing the Noctilux consistently with the 25mm-ish EBLs of the R and R2. Anyone been doing that regularly?
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Old 03-04-2008   #26
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Quote:
Originally Posted by BillBingham2
Can you take the 135 up to 3.5 and 2.8 please?

Thanks.

B2 (;->
Just updated the above picture and emailed you the sheet.

Cheers,

Roland.
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Old 03-04-2008   #27
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Quote:
Originally Posted by Anupam Basu
I thought the rule of thumb was the EBL should be equal to or greater than the physical diaphragm opening for the aperture. Given that, one would need at least a 50mm EBL to focus the Noctilux. I wouldn't bet on reliably focusing the Noctilux consistently with the 25mm-ish EBLs of the R and R2. Anyone been doing that regularly?
Not the 50/1, but I have reliably used the 50/1.2 on the R2, Anupam.

Note that the above table does not account for minimum focus. For example, the 135/2.8 focuses down to 1.5m (? out of memory), the Leica 50/1 to 1m, and the newest Leica 50/1.4 to .7m, which makes the 50/1.4 practically as hard to focus as the 50/1. The worst lens to focus, IMO, is the 75/1.4 at .7m ....

Quote:
Originally Posted by digitalintrigue
Roland, for completeness you might want to add the 105/2.5.
I'll let it sit for a while, maybe we get some more requests ....
How is "my" 105 doing, BTW ?

Last edited by ferider : 03-04-2008 at 12:20.
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Old 03-04-2008   #28
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While we're having fun, here's a universal graph based on a .030 CoC. It's just a quick grab out of Apple's Grapher utility.

The Y axis is required EBL, and the X axis is aperture. The 35, 50, 75, 90, and 135 focal length curves are labeled.

No warranty express or implied.
Attached Images
File Type: jpg ebl.jpg (140.0 KB, 69 views)
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Old 03-04-2008   #29
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Roland,

This would be a great tool for a Marketing person to use to figure out what is the right length for a particular mix of lenses. Not that there would ever be that big a market again, but it's very cool.

Thank you Sir!

B2 (;->
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Old 03-04-2008   #30
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Quote:
Originally Posted by ampguy
...
Would be interesting to see if this table corresponds to other users experiences, I'd guess not, or who in their right mind would use a Bessa or CL??!!
...
Well..
I have a Bessa R and I have never been able to focus correctly the Jupiter 9 at f2, it start looking OK at f4.

I know it may be because it is Russian but in my opinion the J9 myth has born because of the short rangefinder base of many cameras out there like the Bessa..
R.
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Old 03-04-2008   #31
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Quote:
Originally Posted by ferider
Just updated the above picture and emailed you the sheet.

Cheers,

Roland.
Would you be so kind to post it somewhere on the net?
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Old 03-04-2008   #32
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I can only post pictures on my smugmug account, but maybe somebody else
can host it ?
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Beware
Old 03-04-2008   #33
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Beware

Quote:
Originally Posted by digitalintrigue
How 'bout a request for 43mm Pentax? Although any focal length under 50 is a not an issue...

*Your* 105 is doing great. Hey, come to think of it, I also bought one from Bill (F mount.)
It is an addictive lens. Beware.

I use to make fun of people having so many 50mm lenses, then I looked at the fact that I had four 105/2.5 (S, LTM, F and F AIs (ok the last one a lens I gave my wife years back that I now have)) and two CV 25/4 (S and LTM).

BTW, John asked me for your address so I think this is a fast turn around from him. A good sign.

B2 (;->
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Well......
Old 03-04-2008   #34
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Well......

Quote:
Originally Posted by Roberto
I know it may be because it is Russian but in my opinion the J9 myth has born because of the short rangefinder base of many cameras out there like the Bessa..
R.
No, there's a lot of truth to it. I had a J9 on my Bessa T, my Leica M6 and M4-P testing it and it was off. Have a number of folks around the world with similar issues (the focus being off of dead on a couple to four inches). Went to a Nikkor 85/2, SPOT ON with every camera.

B2 (;->
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Old 03-04-2008   #35
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OK, here's a new chart with limit lines for common bodies.

[edit: updated the chart for better readability]
Attached Images
File Type: jpg EBL chart small.jpg (175.8 KB, 106 views)
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Last edited by John Noble : 03-04-2008 at 13:32.
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Old 03-04-2008   #36
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Quote:
Originally Posted by BillBingham2
No, there's a lot of truth to it. I had a J9 on my Bessa T, my Leica M6 and M4-P testing it and it was off. Have a number of folks around the world with similar issues (the focus being off of dead on a couple to four inches). Went to a Nikkor 85/2, SPOT ON with every camera.

B2 (;->
This is me focusing an N 85/2 on a friend's RD1 (no magnifier) -- and failing miserably. I've tried on R3 and R2 with no success.

Photo by Robert



Roland.
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Old 03-04-2008   #37
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The RD1 and R2 does not surprise me, the R3 does, but everyone has off days.

B2 (;->
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Old 03-04-2008   #38
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Quote:
Originally Posted by John Noble
OK, here's a new chart with limit lines for common bodies.
Tres cool, John !
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Old 03-04-2008   #39
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Now.. we need to add all of the FSU cameras...
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Yes
Old 03-04-2008   #40
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Yes

CL and lens were CLA'd at the same time. Close focus at f2 hit rate was maybe 80-90%, partially IMHO due to smaller patch RF than larger M's and trying to use it indoors. Worked perfect at F2 on later larger M's and 2 RD1s.

I don't know what to say about the RD1 and 75/1.4, it's not 100%, but you can see for yourself here:

http://matsumura.smugmug.com/gallery...xbjR#255483561

Quote:
Originally Posted by LCT
Indeed it is not normal at all. At f/1.4 your 75 is way out of the accuracy range of the Epson. It is even very difficult to focus on the M8. Also, the .72x M6 has a longer EBL than the R-D1 (w/o magnifier) and the 40/2 should not have any problem with your CL at any aperture IMHO. Did you have the 40/2 cla'd as well?
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