CV SWH 15/4.5 in LTM, a big disappointment

noimmunity

scratch my niche
Local time
3:29 PM
Joined
Jul 1, 2007
Messages
3,102
I just picked up a lens for my M8 I'd wanted for a long time, the CV Super Wide Heliar 15/4.5 in LTM mount. This lens has received a lot of very positive press, so I expected a lot. Preliminary use shows however that even on the M8, the corners are simply not sharp wide open at infinity.

A quick comparison of 100% crops with the ZM C Biogon 21/4.5

http://www.rangefinderforum.com/photopost/showphoto.php?photo=146068&ppuser=14224

http://www.rangefinderforum.com/photopost/showphoto.php?photo=146069&ppuser=14224

Is this due to sample variation on the CV? Or is the CV just like that? I know the M Mount version is supposed to have the same design, but is it any different?
 

Attachments

  • L1005462.jpg
    L1005462.jpg
    81.6 KB · Views: 0
  • L1005463.jpg
    L1005463.jpg
    124.6 KB · Views: 0
I agree. The 15 CV lens vignettes at the corners all the way to f/8 on my Epson R-D1 and is slightly better on the M8. In my experience it's really brilliant on a fim camera. I have a 19mm Canon f/3.5 FL which is horrible on the RD-1, just OK on the M8, but wonderful with film. The rear element protrusion and close proximity to the sensor is the problem, I think. With film, all the problems go away. YMMV.
 
Well, obviously, I'm gonna have to try my copy of this lens on film.

But I was pretty sure I had read people were using it successfully on the M8. Guess we all have different definitions of "successfully" depending on the look desired.

I got this lens specifically for use on the M8, specifically for landscape, a situation in which I really want corner-to-cropped-corner sharpness.
 
I owned the lens for a long while and used it on the M7, M8 and M9. With the M7 it worked just as well as any other lens though having to remember to adjust the exposure compensation +1 made it slightly annoying but all wides are like that. On the M8 it worked amazingly well. On the M9 I liked it but could not deal with the ugly colour shift in the corners which eventually led me to sell it. There's a fix for it but I really don't have the time to do software manipulations to every photo.I know a NY Times photographer that loves the M mount version of the lens on his M8 and swears by it.
 
I use the M mount version which I've manually coded for my M8. I do see some mild vignetting in the corners, but the lens looks pretty good for what it is. I would definitely try another lens / LTM adapter before giving up on it.
 
Do you have another LTM to M adapter you could try? Is it just the corners?

B2 (;->

I'm using a Milich adapter, which I originally coded for the WATE, but then decided, upon reading other people's experience, to code as a 21 Elmarit ASPH. The problem isn't the vignetting, it's the lack of sharpness. The center is, of course, sharper (still not at the level of the ZM 21/4.5).
 
I'm not wondering about coding but looking at the adapter as injecting a variable in to the sharpness equation. Could it be a 1/10 of a millimeter off one way or another? This might be more of an issue with digital than film.

It might just be a miss adjusted lens. Did you get it new or used? Did the previous owner use it on digital (quicker to see results)?

B2
 
I'm not wondering about coding but looking at the adapter as injecting a variable in to the sharpness equation. Could it be a 1/10 of a millimeter off one way or another? This might be more of an issue with digital than film.

It might just be a miss adjusted lens. Did you get it new or used? Did the previous owner use it on digital (quicker to see results)?

B2

I picked it up from a fellow RFF member who had been using it on an M8, but now has a WATE. He did mention the WATE being much sharper.

FWIW, I had the lens recognition turned off for these two frames (because my ZM C Biogon can't be coded, as it had the wrong flange).

I have a couple of other adapters that I can exchange and try out to see if that makes a difference.
 
Should be sharp in the corners at infinity. Try uncoding, turning off lens detection, and different size (thicker or thinner) LTM/M adapters until corners are sharp.
 
Used that lens for quite a while until I could acquire the in my view little sharper 12mm. Had no problems with the 15mm on the M8.2 but never used it fully open, always at f8 or below. On the R-D1s it was horrible in the corners, not so on the M8.2.


On the M8.2:
3929045901_75c216a744_b.jpg
 
Jon,

if your lens behaves symmetrically, meaning the center is sharper than the corners, and all 4 corners are equally soft, it is probably OK.

Counter-intuitively (for me at least), the wider you go, the more sensitve the system will be to LTM adapter variations (due to thinner Depth of Focus). For a super-wide, a tiny variation can have huge impact.

You can check by focusing on something closer than infinity (like a brick-wall - sorry), and do some focus bracketing. See what happens. Then you can decide if your adapter might be too thin or too thick. If it's too thick you can grind the adapter with sand paper, if it's too thin, you can add some teflon tape between adapter and lens, or shim the lens.

My bet is that your Milich adapter is a teeny bit too thick.

Good luck,

Roland.
 
good points Roland. I've noticed that a ~0.7mm shim (thicker adapter) on a 50 LTM will give me just 10 inches or so closer focus, but on a 28 LTM, will give me about ~2 feet.

Having a variety of shims and different thickness adapters is great with EVIL/direct view cameras. Lens that focus past infinity also help.

RF's gain little benefit here, but digital makes it a bit less painful.
 
"which actually has massive DoF, all things considered"

Yes but I could be mistaken here, but massive depth of field in front of the lens means very shallow depth of focus behind the lenswhich means that wide angle lenses are especially susceptible to alignment issues such as one would encounter with a bad LTM adapter.
 
My CV 15 sucks as well on the M8/M9. Fine for film, but trash for digital. I use a Voigtlander LTM adapter.

If you can afford it, the 18/4 ZM is excellent. I had the mount changed to a Milich brass one for proper coding.
 
Last edited:
Back
Top Bottom