PDA

View Full Version : Sinar P2 4x5 -> 8x10 DoF scale



BennehBoy
2-May-2008, 02:14
I've just purchased an 8x10 conversion kit for my P2 4x5, is there any way to continue enjoying the benefits of the DoF calculation scale when using the 8x10 kit? I've not got any literature since everything has been bought used.

Would any kind soul be willing to scan/photocopy a user guide/manual for me?

Peter De Smidt
2-May-2008, 19:19
Hm. Contact Sinar. I expect that there's a multiformat piece of tape that could be used. Otherwise you can read Tuan's right up on depth of field on the Large Format Photography homepage. This will give you various apertures for a given mm focus spread. Plus this way you decide what counts as acceptable depth of field, not Sinar.

erie patsellis
2-May-2008, 22:21
Ben,
my 8x10/4x5 P has 2 scales, one for 4x5 and one for 8x10. I'd imagine you can get the piece of tape inexpensively. (now I only need to get the darn old oil cleared out of the thing so it works right)


erie

BennehBoy
3-May-2008, 09:37
Hmm, do you think it would be a part that could be ordered direct from Sinar-Bron?

Andrew_4548
3-May-2008, 10:25
Ben,

It might be a bit quicker / easier trying the English distributor:

Image 2 Output Ltd.
Unit 19
The io Centre
Hearle Way
Hatfield Business Park
Hatfield
Herts AL10 9EW

Phone: (+44) 1707 2827 10
Fax: (+44) 1707 2697 64
E-mail: info@image2output.com
Website: www.image2output.com/

I don't know anything about them as things have moved on since I used my P2. I got the info from www.sinar.ch.

BennehBoy
3-May-2008, 13:19
Thanks.

aduncanson
3-May-2008, 16:02
my 8x10/4x5 P has 2 scales, one for 4x5 and one for 8x10. I'd imagine you can get the piece of tape inexpensively.


Is there a simple (or even a not so simple) relationship between the 4x5 and the 8x10 scales? For example if the 8x10 scale is always a stop or two smaller than the 4x5 scale then there may be no need to buy the part. One could just remember to convert.

I recall that the Sinar system directly measures the depth of FOCUS by driving the rear standard from one extreme of the subject to the other. You then focus on the midpoint and take the f-stop to be half the depth of FOCUS divided by the circle of confusion. The difference between the 4x5 & 8x10 scales would only be a different choice for circle of confusion. I don't know about Sinar, but I find I can never rely on a camera maker's assumptions for circle of confusion. Even my medium format Fuji rangefinder cameras seem to assume that I am making a 4"x6" print. Your choice for circle of confusion should depend on how you are going to enlarge and view the image, as well as the standard for sharpness that you require.

I am trying to say that you may find that you can use your 4x5 scale either as is, or by always adjusting by a fixed number of stops.

Peter De Smidt
3-May-2008, 17:12
I don't know about Sinar, but I find I can never rely on a camera maker's assumptions for circle of confusion. Even my medium format Fuji rangefinder cameras seem to assume that I am making a 4"x6" print. Your choice for circle of confusion should depend on how you are going to enlarge and view the image, as well as the standard for sharpness that you require.
.

This is absolutely true. That's why I recommend reading Tuan's article on depth of field. http://www.largeformatphotography.info/fstop.html

Then simply have a chart of ideal f-stops for differences in focus position of the rear standard. For example, 4mm might be f16. (I don't have my chart handy, and so that's just a guess.)

BennehBoy
4-May-2008, 01:47
OK, read that, guess I can manage without the scale :)