Pentax 645 lenses on Nikon D70

[genazzano]

I used to shoot a lot with my Pentax 645 which I loved. These days I routinely shoot with my Nikon D70 and the various Pentax 645 lenses. My favorite is the 45mm f/2.8 shot with a Nikon PK13 extension wide open at shutter speeds of 1/1000 to 1/8000.


This is a link to my album of 67 images taken in our gardens in spring.

www.flickr.com/photos/59013639@N04/sets/72157626987996416/

[Rachel]

I loved using my Mamiya 645J, especially with the waist level finder, and built up quite a collection of lenses and accessories. I recently acquired an adapter to use the lenses on my Canon 5D but have not had a shoot yet.

[truls]

Aug 9, 2014 7:36:47 GMT -5 genazzano said:

I used to shoot a lot with my Pentax 645 which I loved. These days I routinely shoot with my Nikon D70 and the various Pentax 645 lenses. My favorite is the 45mm f/2.8 shot with a Nikon PK13 extension wide open at shutter speeds of 1/1000 to 1/8000.


This is a link to my album of 67 images taken in our gardens in spring.

Lovely images, you have a high general standard in framing and exposure. I think the bokeh is very good from your lens, pleasing to the eye.

[genazzano]

Rachel: let me know if you see a difference with the 645 lenses on the Canon. I really like what I see through the viewfinder and it seems very different from my VF Nikkors. It's probably purely psychological.

Thank you Truls.

I took these just before taking my break, so to speak. Now the challenge is to get back to photography and start shooting again.

Ciao!

David

[genazzano]

I am going through my photos to organise them on my new site. This is one of those that I took with my D70 mounted on the PB6 bellows with an old enlarger Tessar lens. I found the resolution to be quite remarkable. My Nikkor f/1.4 50mm can't get close. The biggest problem was lighting the area of the Contax I. I ended up using a halogen desk light. It would appear that the resolution is down around 5 microns or so, or have I made an error in my foggy brain?

The green corrosion has a gem like quality.



David

[Stephen]

1 micron is 1000th of a mm, so resolving 5 micron is not difficult. In a macro set up comparisons with normal lens resolution are just not on, and very misleading.

The image resolving capability is limited only by the digital target capacity, the resolvable image that can be focused on the target will contain no more or less pixels than the full frame of the sensor.

At high magnification of say over 40x then the resolution possible remains the same, but the Image Size has increased to show finer details.

Given a reasonable sensor size it would certainly be able to resolve well under a micron, as long as the lens can work at the magnification involved.

Tessars in particular are all excellent at high magnifications.

Stephen.

[hansz]

A very good (research) microscope has a minimum limit of resolution of 1,3 x E-4 mm using violet light.
I suspect 1 micron will be a hell of a job...
Source: Philips, Mineral Optics, Freeman, 1971.

[Stephen]

Not so difficult, I had to make British Standard test needles with a 32 micron flat tip, which was examined under a microscope fitted with a micron scale graticule so that the exact diameter of the flat could be measured to a micron. As we made microscopes, an old unit was dug out, I think it was 100x, but not sure. To make the flat more visible a gold prism beam splitter was used to shine red light on to the flat. The flat were hand stoned, in a jig, with finest arkansas stone.
The needles were 1mm diameter with a 7 deg taper to the flat, and formed the basis of tar and pitch testing for grades, dependent on how far the test needle went into samples, driven by a standard force.
Stephen.

[Stephen]

A quick check on the net shows that a 100x objective would resolve a field of view of approx 179 micron, with a 10x eyepiece, so this sounds like the set up used, as the graticule scale was 100 divisions of 1 micron. I do not remember what power the eyepiece was exactly, there was a box full and I found one that worked!
A camera can substitute for the eyepiece or look into the eyepiece, I took shots at the time with my Olympus OM1, needing about 30 seconds to expose.

[genazzano]

Back seven years ago I would have loved this discussion since my life had been designing optical systems and using light microscopes. I went back to check one of my own publications and I must confess, I don't really understand them anymore. Anyway... I liked the jewel like green verdigris and I did it at home with a bunch of used stuff from ebay.

[Stephen]

After a search, a quickly scanned shot of one of the 32 micron tips, this shot has no graticle in it. Must have been done to show the overall size. In green light, with a red spot on the flat via gold beam splitter.
Stephen.