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View Full Version here: : [NOT REQUIRED] Pentax 6x7 lens to QSI583wsg adapter


vic4loc
27-01-2012, 07:28 PM
Looking for Pentax 6x7 lens to QSI583wsg adapter, particularly for the 150mm f/2.8 or 200mm f/4 lenses.

Can buy second hand or refer to anybody that could make it.

Victor.

phomer
27-01-2012, 08:22 PM
You should try precise parts.

http://www.preciseparts.com/ppmain/home.html

Regards

Paul Homer

DavidTrap
27-01-2012, 09:15 PM
I agree with the suggestion to try Precise Parts.

You'll need to work out the thickness of the adaptor, but if it can be built, they are your guys. Won't be cheap though. I have the Nikon adaptor for my QSI. I had to buy the WS (non OAG) front as well because the backfocus of a camera lens was too long for the WSG front. Lots of calculation and measuring to be done.

All the best,


DT

vic4loc
27-01-2012, 09:25 PM
Thank you Paul, I will take a look at their site.

Victor.

vic4loc
27-01-2012, 09:34 PM
Had a look at their site, they are pretty good! :) So far looks like I might be ok.

Below are my calculations... please correct me if I'm wrong:

Pentax 67 lens focal length: 84.9mm

QSI583wsg with T-mount back focus: 50.17mm
Adjustment for filter (Astronomik 1mm thick): -0.33mm
Net back focus for QSI = 50.17 - 0.33 = 49.84mm

Adapter thickness = 84.9 - 49.84 = 35.06mm

Estimated cost from Precise Parts: $330 + $30 shipping.. yikes :)


Victor.

DavidTrap
28-01-2012, 07:03 AM
You need to know the distance between the "mounting bayonet" of the lens and the imaging plane of a Pentax 6x7 camera. If this is 84.9mm, then you're starting from the right point and your calculations look right to me.

DT

phomer
28-01-2012, 08:26 AM
Victor,

The reason these things are relatively expensive is they are one off products. If you let Precise parts know what camera and lenses you have they will do the calculations for you. If you do it all yourself you are taking responsibilty - something you would probably not want.

I found them very helpful and professional. In the end they managed to do what noone else could - produce an adaptor for Pentax 35mm lenses and it works perfectly.

Regards

DavidTrap
28-01-2012, 09:35 AM
I agree with Paul's comments.

I sent them an email and explained what I was trying to do. They double checked my calculations before producing the item.

DT

DavidTrap
28-01-2012, 09:37 AM
Another suggestion. I'd investigate the merits of switching to the larger faceplate on the WSG. It might give you a larger opening and allow you to take advantage of the faster f-ratio of the camera lens. It is a little thicker than the T-Mount faceplate, so would change your calculations.

DT

Joshua Bunn
18-02-2012, 01:53 PM
Another alternative you could try is buying a pentax 67 to EOS adapter off ebay for $45 then taking it to an engineering shop to remove the EOS adapter and machine a plate which fits to your QSI camera to fit on where the EOS edapter was. Im not familiar with the mounting face of QSI cameras though. This is what i did with my SBIG STL and Pentax 67 300mm lense.
I havent checked focus at infinity yet but close focus works. but all should be good if my calcs were correct.

Josh