cv15mm f4.5 asph 2nd vers. fixed lens shade?

[brill64]

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..in order to avoid having to correct vignetting on the m9 in post, i want to fit a center graduated filter. i've located a 52mm dia. second-hand but the lens shade of the (latest version) cv15 gets seriously in the way. does anyone know, short of going at it with a hack saw blade if the lens shade can be removed from the lens leaving the filter thread in place?

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[brill64]

the center filter, although 52mm dia. has a stepped outer ring which is wider in diameter than the petal lens shade of the cv15 which gets in the way..this lens is currently a back-up since the 16-18-21 tri-elmar has gone back to solms for fixing..hence the current dilemma:confused:

[C_R]

the center filter, although 52mm dia. has a stepped outer ring which is wider in diameter than the petal lens shade of the cv15 which gets in the way..this lens is currently a back-up since the 16-18-21 tri-elmar has gone back to solms for fixing..hence the current dilemma:confused:

 

I would not manipulate the lens, instead I would ask an optician to put the center filter glass into another mount (for example, a cheap slim UV filter). I have some 52 mm custom made grad ND filters of this kind, works fine for my CV15II.

 

BTW, would be interesting to know the maker of your center filter, I would buy a new one if I knew where...

 

Cheers

 

Carsten

[jaapv]

Err - if the filter is 52 mm, does the centre spot not cover the entire lens instead of just the centre? It is a lot simpler and more controlled to correct vignetting in postprocessing.

[peter_n]

I would not manipulate the lens, instead I would ask an optician to put the center filter glass into another mount (for example, a cheap slim UV filter). I have some 52 mm custom made grad ND filters of this kind, works fine for my CV15II.

Good idea, I wouldn't fancy taking the hood off this lens (even if you can that is) and I haven't seen any 52mm filters of the kind you're looking for. For some reason the slim 52mm filters can be cheaper than the regular ones so it may not be an expensive conversion.

[giordano]

It is a lot simpler and more controlled to correct vignetting in postprocessing.

 

The advantage of using a filter (if you can find one that suits the lens) is that you don't get problems with noisy corners. On the other hand you have to increase the exposure by a couple of stops (maybe more) so if you have to increase the ISO setting to allow for that you may get noise all over.

[C_R]

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Err - if the filter is 52 mm, does the centre spot not cover the entire lens instead of just the centre? It is a lot simpler and more controlled to correct vignetting in postprocessing.

 

As I said in an earlier thread: it is not the same, to push the corners two stops or to push the ISO and get the exposure right in-camera. Tonal quality is better in-camera

[brill64]

..coming from using wides on 4x5", the center filter was a necessary evil. for use with cv15m on the m9, it seemed a good way to avoid pixels appearing in the corners of the frame after pp. it's a schneider center filter that i have found 2nd hand and it's almost impossible to find, i would add, at this size. it's also expensive to buy new at around us300. the thread part is 52mm but then the optical part steps out and has a much wider diameter of around 55 or 60mm. the extra glass size plus the frame is what stops it fitting inside the petal lens hood of the cv15m. the center grad spot probably covers the glass but doesn't completely cover the angle of view of the lens i think but is enough to filter out vignetting. i think i could not transfer the glass part to fit into a smaller dia. filter thread, although this is a gifted idea and gives food for thought, thank you! perhaps the 45mm is also of a similar construction and can be transferred to a 52? i will investigate further with some calipers today. thanks for the ideas, it really helps!

[brill64]

I would not manipulate the lens, instead I would ask an optician to put the center filter glass into another mount (for example, a cheap slim UV filter). I have some 52 mm custom made grad ND filters of this kind, works fine for my CV15II.

 

BTW, would be interesting to know the maker of your center filter, I would buy a new one if I knew where...

 

Cheers

 

Carsten

 

did you buy a 52mm center spot grad or was it another size and you had it milled down to 52mm dia.? i'm actually interested to see how you made this. my filter is 52mm thread but the optical part is 58mm inside a stepped outer metal rim of 65mm where an optional lens shade can be screwed in. would you mind to describe how you did it in a bit more detail? I'm not much of an engineer..here is what i have:

[brill64]

i realise that i may be barking up the wrong tree here and apologies for the crudeness of this image but here's the basic issue, comments appreciated:

[C_R]

My custom made filter is a soft grad ND, not a center filter. It was made from a 84x 120 mm Singh-Ray Galen Rowell 2 f-stop soft grad ND Filter, cut out by an optician for 5€ and put into a cheap Tama U-Slim Digital UV Filter ring instead of the UV filter glass.

 

The grad is continuous over the whole diameter, no visible transition.

 

 

The grad ND screwed on

 

 

You should find an optician who can cut to 52 mm, but I am not sure that the grad area is just right to compensate the CV 15 vignette. The Schneider filter was made for a special Schneider lens, right ?

[brill64]

thanks very much for your illustrated reply! i think you might be right about it being designed for a particular lens. i suspect a pc lens on medium or large film format though i don't know which for sure.. cutting the center grad smaller and accurately and placing it closer than it was designed for to the front lens element may indeed prove ineffective. i appreciate your input:) i will still see if i can source someone willing to remove and cut it and how much it will cost..

[peter_n]

I think this might be feasible. Your Schneider filter is a 52 and should go into another 52mm ring without any issues. You'll have no cutting and the kind of ring C_R used should work fine. Attached below is a side-on view of my B+W MRC slim UV filter so you can see how high a 52 slim is on the lens. I have no vignetting with this filter on a 35mm film body.

[brill64]

thank you, peter. the filter thread size i've shown above is indeed 52mm but turn the filter over and the glass diameter is actually 58mm. to fit what i already have into a 52mm filter ring requires it to be ground down which may not be feasible. my dilemma is that i cannot find a 52mm centre spot graduated neutral density filter since it is an odd size and would probably only be specially made in batches. thanks for posting..

 

..gosh, you make me feel ashamed for posting such rough pics!

[peter_n]

oh oh oh I didn't realize it was 58 on the other side. That would not work I think. Too bad... 52mm is an extremely common Nikon size but somehow I doubt you will find a center graduated in that size.