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CV Lens Help and Advice for my M8


chrispatel

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I am llokingot get a voigtlander 35 or 40 Nokton and had a few questions I was hoping others could help with.

 

1. Any opinions of the 35 1.4 vs 40 1.4?

2. Do I need to code the lens?

3. Do I need to use a UV/IR cut filter on the lens?

4. Any other watchouts?

 

Sorry for all the questions

 

Chris:)

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A 35mm or 40mm lens is not all that wide on the M8, so there may be little need for coding. On the topic of lens choices, if you can push for the CV Nokton 35/1.2 (V1 or V2), it's said to be an excellent lens, if a little big.

 

The Summicron 40mm f/2 is another alternative, only one stop slower than either lens you mentioned.

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I try CV 35F1.4 both Single Coated and Muti Coated version and also 40F1.4 on M8 they are lovely lens. It's compact size and match well with M8. From what I play they're equally good just choose what you like. If you serious about black fabric color then you may need IR/UV filter on it.

 

I used to have 35F2 Cron ASPH it's a better lens and tact sharp event at F2, but I didn't like it on M8 due to the DOF is not as shallow as on M9. I can not afford 35 Lux for now. So I try many CVs and finally bought 35F1.2 ASPH II and really love it. I didn't have the UV/IR filter yet but didn't see any problem in field.

 

:D

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Beware of focus shift with those lenses. If yours are calibrated like my CV 35/1.4 SC, focus is OK at f/1.4 - f/2 but shifts seriously at f/2.8 and on. It is mainly visible from f/2.8 to f/5.6 in my case. I would try the lenses before buying them if you can.

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The filter isn't necessary, I don't have one for my 40/2 (nor any coding), I would strongly recommend to try the lens before buying the filter because if you don't like the lens you're stuck with a filter that might not be compatible with the lens you end up with ... however if you feel that the lens is a keeper (or, using a very common filter thread size) it's probably a wise idea to buy one eventually.

 

And lenses with focus shifts are useless in practice, so watch out for that.

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Hi Chris,

a 'test' for focus shift isn't all that complicated, but it is kind of important to make it clear that the 'focus shift' being referenced in this discussion describes an inherent property of the Optical Design of the Lens. It is a phenomena where the plane of sharp focus in the image drawn by a lens moves fore or aft depending on what aperture is being used. It is not a problem generated by quality control gaps or substandard manufacture processes. Some very beloved Leica lenses have designs with focus shift issues: mainly from the Summilux stable iirc.

The Test itself just involves taking a series of images of a fixed object with the camera in a fixed shooting position (on a tripod preferably) starting with the lens wide open and then 1 each as you slowly stop the lens down. Then on the computer compare the series of images to see if the plane of focus in the image shifts forward or back as the lens was stopped down.

*note: there are other issues specific to RF based photography you can stumble into while attempting this test.

 

Welcome to the joys and perils of M Camera Photography.

 

Richard in Michigan

 

A lens design that focus shifts can make wide open and/or nearly wide open shooting with it a very annoying process

 

Thanks for all the advice so far. What would be the best way to test for focus shift in a somewhat quick manner?

 

Chris

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Hi Chris,

a 'test' for focus shift isn't all that complicated, but it is kind of important to make it clear that the 'focus shift' being referenced in this discussion describes an inherent property of the Optical Design of the Lens.

 

Apparently people having different experiences with same kind of lenses. I had a CV 28/2 that experienced focus shift, i.e, anything between f 2.8-8 was impossible to focus correctly. Others are claiming they don't have this problem with this lens.

 

So either focus shift is dependent on individual lenses or people are blind to not see that their pics are OOF ...

 

My educated guess would be that focus shift is a result from optical design, but exaggerated (or even canceled out) by small errors made in manufacturing.

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Sample variation is a well known issue with some cheaper lenses like CV's. Also focus shift depends if one uses film or digital and how the lens is calibrated. If it is set to be sharp at f/2.8 instead of f/1.4 for instance, focus shift will be less visible due to DoF.

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Apparently people having different experiences with same kind of lenses. I had a CV 28/2 that experienced focus shift, i.e, anything between f 2.8-8 was impossible to focus correctly. Others are claiming they don't have this problem with this lens.

 

So either focus shift is dependent on individual lenses or people are blind to not see that their pics are OOF ...

 

My educated guess would be that focus shift is a result from optical design, but exaggerated (or even canceled out) by small errors made in manufacturing.

 

Hi Jonasy!

your educated guess is spot on in that Manufacturing Variability in the construction of a lens can cause a user to experience focus shift issues. It can also be caused by calibration issues in a lens, or miscalibrated rf mechanism, and for that matter the human eye isn't the consistent focusing mechanism we'd wish it to be (especially if one has diabetes). :-D

I know I didn't note any of these variables in my post beyond a mention of there being multiple ways to discover focus shift in a lens because I was trying to 'focus' my post on Lens Design caused Focus Shift. If a user encounters focus shift in their use of a specific lens they might end up in a futile effort to adjust/repair the issue away that might be avoided or attempted more appropriately if they check to see if the Lens was designed with an inherent focus shift depending upon aperture in use.

To the Original Poster: a lens can be quite popular and even highly desirable even with inherent focus shifts. There are folks who lust after and treasure certain Summiluxes that others hate with all their might. For that matter, there are a couple of fast Voigtlander lenses which are quite popular (35 & 40 f1.4's iirc) with focus shift issues which sell quite well because they allow a user to get to f1.4 at 1/10th the cost of a new leica lens. Lens choice is always a personal choice made for multiple reasons ranging from aesthetic to function to practicality.

 

Like I said before Welcome to the world of M photography! It can be a little complicated here. :-D

 

Richard in Michigan

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For CV 35F1.4 / 40F1.4 I just testing it in shop for a short period of time so I can not comment on it's focus accuracy.

 

However, I owned the current version of Ultron 28mmF2 and Nokton 35F1.2 ASPH II and both doesn't have any focus shift issue on my M8 and 8.2 at all aperture value. It's both sharp event at wide open. (Sure I didn't mean it's as sharp as Leica ASPH, but it still sharp enough to make me happy)

 

The lens that I have focus shift issue is Zeiss Sonnar 50/1.5 at close focus distance it's only accurate to use at F2.8, but for shooting subject further away the problem is gone and the focus is correct at all aperture (I think it's not a lens fault, it's just limited of old lens design without a floating element optic)

 

I've tested my new Ultron and Nokton last week they seem to work well considering for their price. (Not a nice photo, just tested the lens)

 

Ultron 28F2

http://farm8.staticflickr.com/7014/6695802637_6b8ee61d59_b.jpg

 

Nokton 35F1.2

http://farm8.staticflickr.com/7029/6736377507_588c4e5c95_b.jpg

http://farm8.staticflickr.com/7009/6736379941_cccf35e492_b.jpg

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CV lenses are optimized for cost, not quality. Every product I have ever purchased from them has some flaw like a 25 mm that is unuseable soft on center to left side and a 75 mm finder with crooked frame lines.

 

Just for balance, I've tried a few Voigtlander lenses and they have all been excellent, maybe I'm just lucky or maybe Tobey has been unlucky!

 

If you buy new, and you turn out to have an issue you just swap it, no problem.

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