D800E & Medium format lenses?

[gurtch]

Hi all:
i use a Sony A900 with Minolta/Sony/Zeiss lenses. I also have an NEX7 that I use an adpter and full frame A900 lenses. Because of the smaller sensor, and laarger image circle of the full frame lenses, ther is a "crop factor" of 1.5. Here is my question: I also use a* Pentax 645D, and have several beautiful long lenses, such as the manual focus 150, 200, 300, and 1.4x ( matched for the 300 only). These lenses all have aaperature rings, and there is an adapter ring to attach these lenses to Nikon FF. Since the 645 lenses weere designed for a medium format image circle, i would assume there is also a crop factor when used on 35mm FF? What would that crop factor be?I preordered a D800E, and purchased a 14-24 Nikkor, and 18mm Zeiss ZF.2, but nothing on the long end which I only seldom use, so the inconvenience of an adapter would not be too big a deal.
Thanks in advance
Dave in NJ

 

[Shashin]

Dave, focal length is focal length. A 300mm 645 lens on a 35mm camera would be like a 300mm 35mm lens on the same camera. Crop factor is usually referenced to 35mm anyway.

 

[D&A]

Dave,

Good to hear from you. Just to add what Shashin posted....generally many medium format lenses by design didn't necessarily have the resolving power of their 35mm counterparts, so no telling how good lenses like the FA 300 f4 645 lens will be on a 35mm full frame sensor. It may not be as competitive as say the Nikon 300 f4 Af-S. It's definitely worth trying and often times performance may be surprising in the positive sense. If it isn't, the reasons may be fairly obvious.

Please let us know your observations when the time comes. I'm sure we'll all be quite interested, especially for those like myself who use both Pentax MF and also Nikon. Thanks!

Dave (D&A)

 

[Stefan Steib]

Dave

there is a nice little tool/App for the iPhone that I´m using permanently, for demos, for my own work and also for tuition as it is really simple and intuitive:

It´s called "Angle of View" costs 2 $ and will enable you to compare the image angle (diagonal, vertical and horizontal) for up to 5 preset format buttons ( I use 4x5", IQ180, P45+,35mm Full format and APS-C.
there is a little wheel on the right to chose the focal lenghts and also a slider that will tell you the distance to subject at which size you need for the given focal length.
The diagonal image angle can then be compared and will tell you exactly how this chosen lens will do on which format . Very easy and very useful !

Greetings from Germany
Stefan

 

[gurtch]

Stefan: I dnt have an iphone, but do have an ipad, so i will see if the app is available for it. Dave (D &A): nice to hear from you.
dave in NJ

 

[gurtch]

Re: D800E & Medium format lenses?
Dave, focal length is focal length. A 300mm 645 lens on a 35mm camera would be like a 300mm 35mm lens on the same camera. Crop factor is usually referenced to 35mm anyway.
I am connfused. Again. A 300 mm lens for 645 has a large image circle. cropping out only the center to 24x36 mm would be like using a longer lens, I thought. Same rational with FF used on APSC? Thanks again.
Dave

 

[Shashin]

Dave, crop factor is always a reference of an angle of view to another particular format, usually 35mm.

If you put a Nikon 300mm lens on your camera, it will have the same angle of view as your Pentax 645 300mm lens on the Nikon. Image circle will have no baring on the angle of view--that is just focal length and format size. If you put your Pentax A 35mm lens on the Nikon, it will have the same angle of view as a Nikon 35mm lens on the D800.

 

[gustavo]

maybe it coudl help you: Rui Salgueiro's field-of-view calculator
I think the answe you are looking for is something similar to 1,5

 

[donaldt]

Dave
think of it as cropping the picture in post production
the lens does not become any longer
you are just cropping the center of the frame, if you then enlarge the cropped frame, it gives you the illusion that you used a longer lens

if you use a 80mm on the 645, it "feels" almost like a 50mm on the FF or 35mm on the APS-C, thats what the crop factor is about

I feel like it is a marketing technique to make smaller sensor looks like there is an advantage using longer lenses but in fact it doesnt
they tell you that if you use a 4/3 system you double the focal length, so using a 400mm f2.8 on a 4/3 is a 800mm f2.8, which is a big lie
using the 400mm f2.8 on the 4/3 is the same as using the 400mm f2.8 on the FF and then crop the center out, thats all

so the lens does not get any longer and the DOV does not change

Re: D800E & Medium format lenses?
Dave, focal length is focal length. A 300mm 645 lens on a 35mm camera would be like a 300mm 35mm lens on the same camera. Crop factor is usually referenced to 35mm anyway.
I am connfused. Again. A 300 mm lens for 645 has a large image circle. cropping out only the center to 24x36 mm would be like using a longer lens, I thought. Same rational with FF used on APSC? Thanks again.
Dave

 

[dmeckert]

i think perhaps the confusion is coming in that crop factor is relative to the sensor/film size, not the lens.

using a 50mm lens as an example...

on 8x10 it's extremely wide, on 645 it's a moderate wide, on 35mm it's a normal, and on 1.5x crop it's a mild telephoto. it's effect is only changed by what it's recording onto.

it doesn't matter if the lens was constructed for large format or crop format. if you take a 50mm constructed for large format, medium format, FX digital, and DX digital, and strap them onto DX camera, you'll get essentially the same image.

given the example of the 300mm and the large image circle...the image circle is only relevant in this instance if the format can utilize it. 300mm on 8x10 is a normal lens, whereas on crop digital it's a long telephoto.