Thinking of trying macro photography with SQ-A...have questions
Hi all! Merry Christmas to everyone first off.
With all of the snow that been flying around and on the ground here lately I've been thinking of trying some macro shots of snowflakes with my SQ-A. Now I've never tried macro at all, let alone on medium format. I have been doing some reading about lens stacking and was hoping to run some stuff by those more in the know than I.
I was thinking about mounting my 150mm PS lens on the camera without an extension ring, then reverse mounting a reasonably fast wide angle prime lens from a 35mm SLR on the front via a filter adapter ring. As long as the reversed lens has 67mm or larger filter threads on it I shouldn't have any issues with image coverage, right?
I found a couple of places that describe how to figure out magnification factor using reversed lenses and such, but they are all for 35mm cameras using 35mm lenses. I know that 75-80mm on MF is about the equivalent FOV as 50mm lens on 35mm film. So I don't know how to figure out magnification and area of focus here. Am I just making this a lot more difficult than it needs to be? I haven't picked out a lens to reverse yet though, but have been picking through lens databases and KEH's as-is lens section looking for lenses with 67mm or larger filter threads that are wide to normal on 35mm that are reasonably fast.
Any help or suggestions here would be really appreciated. Thanks!
Too much trouble. They're scarce but Bronica SQ extension tubes might be a better solution. Same goes for the 110/4 PS macro lens. Hyper close-ups will tricky with the SQ. That's why I opted for macro goodies for my Mamiya RB67 and not my SQ-B.
Originally Posted by Chiron
Maybe I'm just cheap, but I've always had great luck with the "close up" lens sets that screw into the filter threads of the lens. I have a set for my RB67, and get wonderful results with out any exposure compensation needed. Way back when I had the bellows set for my SRT-101, and to me i was more trouble than it was worth. The nice thing for me about the close up sets, is that since all the RB lenses take the same size filter, I can use them on which ever lens I have on the camera.
Merry Christmas to you as well.
Originally Posted by Chiron
And yes, you are making magnification difficult. Basically, magnification is image size to object size. So at 1X, a one inch bug will have an image size of one inch. In 35mm, this will fill the frame, in medium format, will take up a little less than half the linear frame size. So if you know the magnification and frame size, you know how much space the image will take.
Have fun experimenting with this. The best method is the one that gives you the results you like.
Magnification factor is (IIRC)
where F1 represents the focal length of the mounted (primary) lens and F2 represents the focal length of the second (reversed) lens.
To find your effective focal length use this one.
F = (F1 x F2) / (F1 + F2) where F = Total Focal Length, F1 = first lens' focal length, F2 = second lens' focal length.
To find your relative aperture, assemble the lenses and hold a piece of white paper to the end that will mount on the camera. Shine a bright light into it and measure the circle of light that results. Divide that into your effective focal length and arrive at a relative aperture.
And make sure both lenses are focused to infinity. And if you want to mess with different apertures, best to keep the reversed lens wide open and adjust on the mounted lens.
I hope this didn't thoroughly cornfuse you. Been a while since I tried it but I do love my notes.
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I have a feeling your method will not give you sufficient magnification to bring up the detail in the snowflakes (unless you have huge snowflakes .
Essentially, with your intended system the magnification would be:
M = Focal length of prime lens (in mm) x Diopter of reversed lens/1.000
So, the longer your prime lens and the shorter your reversed lens the greater the magnification.
The diopter of your reversed lens is: D = 1000/focal length of reversed lens (in mms)
Using your scheme, you wouldn't need to worry about light loss (as per add-on closeup lenses).
You probably will get vignetting, as a 35mm format lens has less coverage than needed for MF.
I've definitely found light loss with the proposed type of setup. It can be several stops, depending on nominal aperture of the attached lens. The entrance pupil of the attached lens is typically smaller than on the main lens, and I figure that's the reason.
Originally Posted by Galah
Vignetting is likely. I just tried my ETR-Si's 150/3.5 (I think close enough for this purpose) with a 135 format 50/1.8. Definite vignetting, which was reduced by setting the 150mm to its minimum focus distance. A 28/2.8 was worse, and showed a lot of distortion, also. You might have good results with using the 80mm Bronica lens as the attached lens, though I suggest not moving the focusing ring without supporting the 80mm, to reduce strain on the 150's focusing mechanism.
I tried my 75/2.8 on my 150 and distortion was low at the point of focus. There is vignetting, much reduced by setting the 150 at closest focus.
I do use a digital device in my photographic pursuits when necessary.
When someone rags on me for using film, I use a middle digit, upraised.
There is a bellows available for the SQA that will make extreme macro way easier with that camera.
And there it is. KISS. Why didn't I think to mention that. Oy!
If you really get a hankering to have a bellows for your SQA give me a PM. They aren't exactly cheap but you can get a lot of extension.
Originally Posted by glbeas