Pentax 67 for APSC


pschlute

Link Posted 01/10/2019 - 23:18
bforbes wrote:
Thanks Bjørn. What I have in mind is an architectural shot with limited space to move away from the subject. So the lens with the widest field of view would be good. I'm assuming that would be the 45mm 67, but I've got know reference for how that relates to an APSC body.

In that case it does not sound like the 67 system lenses are going to work. If you want a very wide filed of view then 45mm is not it.
Peter



My Flickr page
Last Edited by pschlute on 01/10/2019 - 23:18

womble

Link Posted 02/10/2019 - 07:14
A 45mm lens is a 45mm lens on whatever camera you attach it to. So if you want to know the FOV for APSC, put a 45mm lens on it and look. A 45mm lens on 67 has the same FOV as a 24mm lens on 35mm, or a 16mm lens on APSC. Attaching a 45mm lens designed for 67 to APSC doesn't make it a 16mm lens, it is still a 45mm lens albeit with a huge image circle of which you are only using a small section.

Best wishes, Kris.
Kris Lockyear
It is an illusion that photos are made with the camera… they are made with the eye, heart and head. Henri Cartier-Bresson
Lots of film bodies, a couple of digital ones, too many lenses (mainly older glass) and a Horseman LE 5x4.

My website

bforbes

Link Posted 02/10/2019 - 08:39
bjolester wrote:
The Pentax 67 SMC 45/4 performs like a 45mm lens on aps-c. On the Pentax 67 camera, on the other hand, this lens corresponds roughly to 22mm FOV on a full frame camera or like the DA 15/4 on aps-c.

The Pentax 67 SMC 45/4 is the widest rectilinear lens in the Pentax 67 system, and is among the best performers. Over at the American forum there is a member "Desertscape" (Steve Rasmussen) who has high competence with the P67 lenses and has written reviews of many of them. His review of the SMC 45/4 is very informative, also about sharpness and other characteristics.

I've found a reference that gives the crop factor for 67 lenses as x0.5 so I understand the 22mm on Full Frame but I don't understand how it's 15mm on APSC. If that is what you are saying?
Barrie
Too Old To Die Young

http://www.pentaxphotogallery.com/artists/barrieforbes

HarisF1

Link Posted 02/10/2019 - 11:05
The crop factor from FF to APS-C is around x0.7

In any case, you'd get a similar looking image with 45mm on 67 as you would a 22mm on FF and a 15mm on APS-C.

The bokeh/depth of field will be different.

bjolester

pschlute

Link Posted 02/10/2019 - 11:39
bforbes wrote:


I've found a reference that gives the crop factor for 67 lenses as x0.5 so I understand the 22mm on Full Frame but I don't understand how it's 15mm on APSC. If that is what you are saying?

You have an aps-c camera. Any 45mm lens is going to have the same FOV on your camera. If you use a 6x7 45mm lens it will look very similar to a DA 50mm lens.

You said you want a wide FOV for your pictures. So you are going to need a lens around or below the 20mm mark. Now 6x7 lenses do not come that wide. Because of the larger frame size of 6x7 format, a 45mm lens is a wide angle. But it is only a wide angle on that format.
Peter



My Flickr page

womble

Link Posted 02/10/2019 - 11:44
What confuses the hell out of people is mixing the focal length of lenses with the field-of-view. To get the same field-of-view on different formats, you need a different focal length. Take a lens designed for one format and use it on a different one, you'll get a different field-of-view.

In this case, the original post was hoping that a very wide angle lens for 67 would give a very wide angle lens on APSC. It does exactly the opposite. A 45mm lens is very wide angle on 67, but almost a normal lens on 35mm, and a slight telephoto on APSC.

Bjørn's table shows this perfectly. If you want a 87.7 degree field of view, you need a 46mm lens on 67, but a 15mm lens on APS-C. If you attach that 46mm lens to an APSC camera, your field-of-view would be between 39.6 and 31.4 degrees.
Kris Lockyear
It is an illusion that photos are made with the camera… they are made with the eye, heart and head. Henri Cartier-Bresson
Lots of film bodies, a couple of digital ones, too many lenses (mainly older glass) and a Horseman LE 5x4.

My website

bforbes

Link Posted 02/10/2019 - 23:28
Thank you all. I think the idea is dead
Barrie
Too Old To Die Young

http://www.pentaxphotogallery.com/artists/barrieforbes
Last Edited by bforbes on 02/10/2019 - 23:28
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