Help to determine if the aperture index is right, and if not, how to fix it.

[Pere Casals]

setting the aperture index on a 4x5 lens
[/ATTACH]

I can tell how I checked the same.

First I carefully spot metered a grey card with a Nikon F5 with 50mm 1.8D.

Then I removed the 50mm and I placed the F5 in the back of a view camera (Norma) with a DIY graflock to F Mount adapter,

like that


Then I focused the view camera with the lens I had to check at infinite (to get nominal bellows extension) looking through the F5 viewfinder.

Then I pointed to the grey card with the view camera (without moving focus) and metered again. So I metered TTL both times.


We can guess that the Nikon 50mm f/1.8D (5 groups) has the same transmission than a multicoated LF lens (4 groups).

The SLR 50mm has an additional group, this is 2 additional air-glass surfaces so we can guess that the nikon 50mm 1.8D has 0.995x0.995 = 0.99 , this is the 99% of the transmitance performance of the LF lens, so the same in practice, as a full stop is 50%.


In fact the metering I got with the F5+Nikon 50mm matched pretty exactly the one that I had with F5 on the back of the view camera with LF lens focused at infinite. Note that if the view camera is not focused at infinite this won't work.

Of course you can also use a DSLR for that...

Regards.

[Steve Goldstein]

Years ago I had a shutter come back after a CLA by a very reputable firm with the aperture control lever mounted 180 degrees off. Could this be your problem? It's held by two very tiny screws, and the "repair" took less time to do than to type this.

[LabRat]

Oh, and did I mention my test is to be done outdoors on a brightly lit wall so there is a fairly bright GG that you can still take a reading on as the aperture is stopped down???
(Sorry for the omission!!!)

I use a digital spotmeter pressed against the GG with the spot circle just touching the center X lines and stop down from there... I have made some pretty OK scales for lenses that had no scale, that film tested quite well...

I have also home made a Nikon 35mm mount insert for the film plane that fits in the Graflok tabs (like Pere has) that I use for very close macro, and meter using a Nikon FE camera (that has an extended metering range), but don't forget to subtract the extra distance from the GG/film plane of the adapter, to the 35mm film plane + metering (esp with shorter lenses) when computing bellows draw... (Unless you are rolling the rear standard inward so the 35mm focus is at the same plane where the GG was...)

Steve K

[StuartR]

Hello all, thank you for all the help! I am sorry I did not respond earlier. It was night here and I did not get any notifications!
I am actually leaning towards Steven's explanation as being the right one, but I will call KEH to sort it out.

I am also sorry for the ambiguity. It is a Sinaron W 90mm f/4.5 in a Copal 1 shutter. It came from KEH in Ex+ condition, and they list all their gear as being inspected and tested. Indeed, the condition of the lens is very good, and the shutter seems to fire just fine, and the iris itself does not have any problems in moving.
That said, the aperture index lever is on the bottom of the lens, and the position does not seem correct. I will try to show a photo or two of the problem. The photos are of the moment when the iris first begins to cover the lens. So this is literally wide open...I would normally expect that since this is a 4.5 lens, the iris would begin covering part of the lens immediately after you stop down further than that. So if you choose 5.6 for example, the iris would cover more of the lens than at 4.5. Right now the iris does not cover any of the lens at all until about f/8. The question at this point is can I fix this myself, or does it need to be sent for repair. Again, living in Iceland makes it very inconvenient to return the lens. The return shipping will cost me at least 50 dollars, and I will have to go through a lengthy process of obtaining a refund from the customs office, which might take weeks or months. Seeing as the lens appears to be otherwise in good condition, I would rather just try to fix it.

P.S. I put the lens on a Sinar board just to test to see what the angle of view and vignetting looked like on my studio monorail, my normal use for this would be on a Linhof board in an Ebony.

[StuartR]

Eh? Wot? B/W film has broad exposure latitude, +/- 1/6 stop makes no practical difference.

I am sorry Dan, I was not clear. I meant that +/- 1/6th would not be important to me. I just want a lens that I can trust to within about 1/2 of a stop.

As for the jamming, the lever moves smoothly on the board, but not when mounted on the camera. The lever moves past the bottom edge of the Linhof type board, and it rubs against the front of the camera. I would rather the lever was on the top of the lens anyway, like every other large format lens I use.

[Pere Casals]

the extra distance from the GG/film plane of the adapter.... ...when computing bellows draw...

Steve K

For bellows compensation... a tip I use when metering with a SLR in the back of the view camera: With the SLR in the the back I focus to the subject by using the viewfinder and I use the SLR as a spot meter,that reading will need no bellows compensation when I place the GG in place and I focus again at the subject, as when I focus with the GG I'm to move it just the "the extra distance from the GG/film plane of the adapter, to the 35mm film plane".

As the reading with SLR was made TTL and the subject in focus the reading can be used directly without any correction.

Even in the case a filter is used it is possible to evalute the resulting contrast of the scene, if a filter is used to darken sky, for example, and directly using those readings. The F5 (and modern DSLR) has the advantage of having a RGB class photometer, problem is weight.

What I like of having a DSLR to help the Norma is that one can make a test shot and see the histograms, for Velvia it is also useful to see histogram for each channel, and to evaluate suitable manual color correction when color temp drops.

It is very funny to see some LF photographers with a D810 photometer metering for a firewood camera (I use a consumer one)

[StuartR]

It is actually the Rodenstock 90mm 4.5, older version before the green stripe,with Sinar's name on it.

Since Iceland belongs to the EEA can't you send it back to Germany for service at the Rodenstock factory. Switzerland is not a member nation but Sinar is owned by Leica in Germany so they might also be able to help you.

Hi Bob, thanks for the help. Iceland is in the EEA, but not the EU. Unfortunately this means that I would have to pay VAT on the repair and deal with customs each way. The minimum cost to do this would likely be 400-500 dollars (shipping both ways, service and taxes), which is nearly as much as I paid for the lens.

[Bob Salomon]

Hi Bob, thanks for the help. Iceland is in the EEA, but not the EU. Unfortunately this means that I would have to pay VAT on the repair and deal with customs each way. The minimum cost to do this would likely be 400-500 dollars (shipping both ways, service and taxes), which is nearly as much as I paid for the lens.

Germany does not collect VAT on items made in the EU that are sent into the EU and that will be sent back out of the EU after repair. Contact the German Consulate for the correct details and paper work. We did this from the U.S. On a normal basis.

[StuartR]

Hi Bob, it is not the Germans I am worried about. I will pay an additional 24% VAT on the total FOB worth of the repair (including shipping) and I also have to file paperwork with Icelandic customs that costs about 30 dollars to prove that I sent the item out for repair. Please believe me that I know what I am talking about in this regard. I am a professional photographer and have dealt with living here and arranging repairs of gear to Germany and the US. I was hoping of people could just look at the pictures and read what I wrote and see if it is indeed wrong, and if so, if it is something I can easily fix. Thank you!

[Dan Fromm]

Thanks for the images. Image 1 looks quite normal, in image 2 the scale is on upside down and backwards. Undo the two screws that hold it to the shutter barrel, turn the scale right side up and replace, replace the screws.