Vignetting using 77mm filter adapter on 15mm Heliar!

[ncc1701]

Has anyone experienced this?

I know the adapter is made for the 12 but I thought it would be ok on the 15.

Thanks in advance for responses

 

[Warroo]

I don't, but tell me, what kind of filter do you use? I am looking for a filter designed to take away the "hotspot" for the 12/5.6 (neutral desity center filter).

 

[laptoprob]

Welcome to the forum!

The problem n vignetting with the 15mm Heliar is because the angle of view is that wide, the light is going through more glass in the corners. Expecially if you use a dark filter like orange, red or pola the difference becomes very clear. Remedy: stopping further down. My avatar is made with 15mm at f4,5. The vignetting is visible but usable to create a natural filter. That's also why I almost never use this lens in 'landscape' position.
I still have to learn to remember to stop down using dark filters. I recently got a red and dark red 72mm filter. I use a 49mm-72mm step up ring with some plastic cap lining to make it fit. I have not tried the dark red filter yet.

Rob.

 

[John Robertson]

I have the adaptor modified to fit the 15mm, I took out the strip of spring steel which clamp it to the lens (carefully and noting how it fits! ) covered it with heat shrink, except for 5mm either end , then put it back. It now fits snugly. Beware however of using filters, usually cheaper ones, with thick rims. They do vignette. However the slim rim B+W is fine.

 

[ncc1701]

I am actually using a dark red Filter and were shot at 5.6.

Also I was using a not so great Tiffen filter!

Here's a sample

 

[Fred]

It might be worth trying some of the larger Cokin type filters and hand holding the lower corner against the little lens hood, you will see some vignetting as the wider angles mean that the light passes more diagonally through the filter. The only sure way is to use a curved dome filter, don't know who makes these.

 

[Fred]

The vignetting using the big square filter will be nothing like as severe as the Tiffen example. You have to hold it at the bottom corner though else you'ss see your finger. Hold it like a diamond and you should be OK but it must be flush with the hood.

 

[John Robertson]

Cokin makes a contraption which fits the tripod thread, and holds square filters in front of the lens, made for compacts , but should also work on the Bessa.

 

[Theo-Prof]

You might want to try a Cokin P-series filter holder. I have used one sucessfully with my CV 15.4.5. I use the Cokin 52mm adapter that I use when I use the Cokin holder on my Nikons. I wrap 4-6 pieces of black electrical tape over the inside edge of the 52mm ring, in essence decreasing the diameter of the opening slighly. The modified ring then attaches to the P-series holder and the whole unit slips over the focusing ring of the lens. I can still read the aperature setting and the focus distance without any problem. With a filter placed in the slot furthest forward in the Cokin holder, the filter just clears the front edge of the hood on the lens. The link below is to my gallery which has a few Kodak Infrared shots taken with the 15mm, deep red filter, and this filter set-up. It is not the most convenient system but it does work with no vignetting.

http://www.rangefinderforum.com/photopost/showgallery.php?cat=5066

I hope this helps,


Kevin

 

[Bafpunt Prose]

I 'd like to do some IR photography with the 15mm Heliar. I don't understand how one fixes a filter holder to the lens; no filterthread is provided ...?

 

[John Robertson]

I think this will help.
http://www.cokin.fr/ico15-B.html
I have one of these for my digicompact thingy!! I have just tried it on the R2 with the 15mm lens fitted. If you put the filter in the furthest forward slot then adjust the holder so the petal hood of the lens is just touching the inside of the filter, I would think there would be minimal if any vignetting.

 

[Theo-Prof]

I 'd like to do some IR photography with the 15mm Heliar. I don't understand how one fixes a filter holder to the lens; no filterthread is provided ...?

The set-up I described above has the filter holder slip over the lens barrell and onto the focusing ring. This places the lens deeply into the holder so there is no vignetting. Another person in this thread indicated that he uses a smaller diameter step-up ring (43 or49mm, I don't remember) and a 72mm filter. I assume that he slips the step-up ring over the front of the lens barrell, the "hood" portion of this lens. Even without filter threads you can always find a way to get a filter in front of the lens.

The Cokin "A" sized device that attaches to the bottom of the camera originally came out several years ago for use with point and shoot cameras. I have never tried this with the CV15. I fear that the filter will be too small for the coverage of the 15mm lens.

Kevin

 

[John Robertson]

Provided you put the filter in the furthest outside slot and abut the filter against the petal lens hood it does not seem to vignette.

 

[Theo-Prof]

John,

This is good to know. The holder you describe would probably be more secure than the one I have used. However, I would have to get the "A" sized filters while I already own the "P" sized filters.

Kevin

 

[laptoprob]

49-72mm adapter

49-72mm adapter

Another person in this thread indicated that he uses a smaller diameter step-up ring (43 or49mm, I don't remember) and a 72mm filter. I assume that he slips the step-up ring over the front of the lens barrell, the "hood" portion of this lens.

It was I, Kevin. It works perfectly. I have one adapter with holes to see a pola filter through the viewfinder. Another with a plastic lining to make it fit over the hood. And another I am still trying to find the correct plastic bottle or ring for.

Vignetting occurs mainly with me with dark filters, due to the direction of light passing it. Stopping down helps.

 

[Theo-Prof]

Thanks Bob, I guess I was too lazy to scroll up to find who mentioned the step-up ring set-up. I will have to try this. I know I have several different step-up rings around the house somewhere. Perhaps I could use a 49-52 step-up with a 52-72/77 step-up or some other combination. I had thought of trying this but I was afraid that if I just used, say, a 49 to 72/77 step-up ring that I would not be able to slide the whoe unit back far enough over the "hood" of the lens, thus not eliminating the danger of vignetting. Before I tried the Cokin filter set-up I had already discovered how easy it is to get your fingers in the shot with this lens.

Kevin

 

[laptoprob]

You will have to try if it works, does not vignette with two rings. No experience there.
I already made quite some mistakes, finger shots lazily holding the 72mm filter by hand. I never want to do that again, therefore I want more step rings and plastic rings in them.

I even got a 8x red filter... still have to try that effect!

 

[galaxenspreside]

The filter holder itself vignettes, lets modify it!

The filter holder itself vignettes, lets modify it!

I just bought the Heliar 15mm and the 77mm filter holder for the CV 12mm to use on the 15mm. It turned out that the filter holder itself did the vignetting. It was easy to see as the inner rim protruded significantly as compared to the lens shade which has cutouts on the sides and the corners.

The problem as I see it is that the aperture adjustment ring hinders the holder to settle sufficiently close to the lens on the 15mm.

My solution was to remove as much aluminum from the back of the ring as possible allowing it to sit closer to the camera body saving just enough of aluminum to hold the tightening spring in place. Then I also removed the inner edge of the from of the holder matching the the lens hood cutouts.

I have attached some illustrations. An example of a photo taken with the filter holder only and a couple of photographs as I did my modifications to the filter holder.

BTW:
A good way of finding out whether a lens vignettes is to open the film compartment and open the shutter using the bulb setting (carefull nut to poke your fingers into the opening as the shutter closes) and viev the lens iris from the corners of the shutter opening. If you see the iris fully without anything obstructing the view in front of it you do not have a problem with vignetting and if you have it you can also see what is caussing it. Moreover as you look from the edge the iris appears eliptical rather than fully circular. This accounts for the normal light falloff of a wideangle lens together with the light hittting the film at an oblique projection further reducing the light intensity. This is the way you normally check that you have not exceeded the covarage of your lens in large format photography when you make tilt/shift/swing movements to adjust the focal plane and perspective correction.

I hope this was of use for someone.

Kind Regards
Richard

 

[galaxenspreside]

...continued

...continued

Two more illustrations of the modified holder: