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# Thread: Using front element only, what can I expect?

1. Paul, Thank you, this info will come in handy. As I was using this method, 2 thoughts came to mind. 1.) Would I not get a more accurate reading if I omitted the shutter and just shined the light behind the front element? 2.) Is taking this measurement actually needed to do the recalculation of aperture? If you are using only the front element to acquire this diameter reading and I am trying to recalculate in order to only use the front element, then they would be the same reading. As the lens is stated as a 210mm f-5.6, that reading would be 37.5mm. So to recalculate I would divide 430mm by the same 37.5mm to equal 11.4666666, f-11-16 split. Which is the figures that Björn has suggested. It would also make sense to me in the fact that I am doubling the focal length of the same lens, therefore I should double the F-stop (5.6x2=11 roughly). Is this true or just for this application?

Björn, tack så mycket (just a guess), you answered the next question as to what that really means. F5.6 marker becomes F11 on the shutter. Now I guess I will need to go read that sticky about calculating bellows extension since they are basically all the way extended. Something tells me I am going to need a bright sunny day for this.

2. Originally Posted by jerk151
Björn, tack så mycket (just a guess), you answered the next question as to what that really means. F5.6 marker becomes F11 on the shutter. Now I guess I will need to go read that sticky about calculating bellows extension since they are basically all the way extended. Something tells me I am going to need a bright sunny day for this.
I'm not an expert, but the f:5.6 convertible Symmar lenses had rear components that were used alone rather than the front. For optical reasons, the rear and front sets were different focal lengths, possibly 375mm for the rear set on the 210. I believe those went from f:5.6 to something like f:12, but the front set may be longer focal length, and so have a smaller f-stop.

You should probably either find lens specs or measure for yourself.

Lee

3. Where is a polaroid when you need it? I have taken the rear element off my 210 Nikkor and it becomes a beautiful portrait lens till you stop it down. I seem to remember that focal length became much longer that way.

4. Dpurdy, As luck would have it, I got a polaroid back in the mail about 4 weeks ago and have not taken the time to use it yet. Coupled w/ the half box of 55 in the refrigerator and I took a couple of shots from the front porch.

I had an extremely hard time focusing. There is enough bellows because I can tell when I have got too far in each direction, but for some reason I just couldn't pin point clarity today.

#1- Exposed for asa25, meter reading was 32-45 split@1 sec, bellows factor was 1.25, I believe around 1/8th of a stop open/longer.

I didn't make the adjustment and shot it at F32 @ 1sec.
[IMG][/IMG]

#2- Exposed for asa25, meter reading was 90 @ 8sec on the dot. same bellows factor so I shot it at a fraction past 8sec.

[IMG][/IMG]
Please don't judge too much on the image itself, I just wanted to do a quick test and I was trying to make it happen during my lunch break.

5. Dear Jerk,
A b it like I expected, somewhat softer in the sharpness than I would expect from a full 4x5 lens, a bit like an Imagon, but not bad at all.
You got your self an other lens !

Have fun, experimenting works

Peter

6. The second shot had some foreground interference that I knew was there, but I wanted to see if it would even be seen. The trellis in the garden across the street is around 25-30 yards/meters away. The tree branches that are going right through the middle of the image are about 4-5 yards/meters away from camera. I will definitely need to shoot some normal B&W and take some time to see what it will really do.

7. Ofcoarse, but now you know that it works !!!!!
The depth of field will be a bit smaller (longer lens now) but that should not be a problemm.

I like this: making something out of something aparently useless.......

Greetings,
Peter

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