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styleshot
5-Feb-2007, 14:07
Hi

Can anyone tell me what 'KODAK Ektar 10 in. ILEX No. 4 Acme Synchro Shutter f6.3' is equal in 35mm please? I will be using it for a 8x10. Also what is the standard lens in 8x10? I am after a 50mm equal lens. Any suggestions?

I read the list of lenses in the thread of LF8x10in but it does not make a lot of sense to me. A bit confused with the coverage and where it says equal 35mm.

Example of 300mm lens it says equal 42mm in 35mm but a lot of people on Ebay says this is a portait lens (should be 80-135mm).

Much appreciated.

Thanks
Mark

BradS
5-Feb-2007, 14:17
Generally speaking, the focal length of the "normal" lens for any given format, is about the same as the diagonal of the format. So, for 8x10 the diagonal of the format is: SQRT(8*8 + 10*10) = sqrt(164) = 12.8 inches. That's about 325 mm.

styleshot
5-Feb-2007, 14:21
Hi Brad

Thanks for the swift reply. That is a very nice brief explanation.

When you say 325mm is that in 8x10 format? So if so what is that equal in 35mm format please.

Thanks
Mark

Oren Grad
5-Feb-2007, 14:27
Mark, measuring by the diagonal of the format, the 10" focal length on 8x10 is roughly equivalent to 35mm on the 35mm format, which makes it semi-wide.

Depending on the uses you have in mind, this may not be an appropriate lens for 8x10. I hope one of the real lens gurus here will jump in and correct me if I'm wrong, but my recollection is that the 10" Ektar will, at best, barely cover 8x10 at infinity focus. If that's correct, then except at very close range, its scope for movement will be quite limited.

Ash
5-Feb-2007, 14:27
well if 12.8in is a 'normal' length for 10x8
and 50mm is a 'normal' length for 35mm

your lens is 10inch. that's (10/12.8) of the normal lens length. 0.78125

so 50mm multiplied by 0.78125 = 39.0625

your equivalent focal length is 39mm for a 35mm camera

Scott Davis
5-Feb-2007, 14:27
The 12" (300mm) is the rough approximate of 50mm for 35mm. So your 10" Ektar (250mm+/-) is like a 35mm lens, more or less.

Here is a decent comparison chart for your information:
http://www.kenmarcamera.com/Equivalent%20Chart.html

For the 8x10, the Commercial Ektar 10" is probably not a good choice as far as coverage is concerned. Kodak also made a 250mm (10") Wide-Field Ektar, which will cover 11x14 with limited movements. 12"/300mm is an ok portrait length for 4x5 or 5x7, but is not so good for 8x10. For 8x10, you want at least a 14"(360mm) lens for portrait work, which is the equivalent of 60mm on 35mm cameras. The larger the format, the shorter the equivalent portrait lens becomes, because once you get beyond 8x10, a head-and-shoulders shot becomes a 1:1 or greater macro shot. Then, those really long lenses do you no good.

neil poulsen
5-Feb-2007, 14:29
About 32mm or 33mm in the 35mm format. I think of 250mm on 8x10 as being a medium wide angle lens.

Is this the wide-field 250mm Ektar?

Oren Grad
5-Feb-2007, 14:29
The diagonal of the actual image area of an 8x10 sheet is more like 312mm. So the calculation was (254/312)*43mm to get the 35-format equivalent.

styleshot
5-Feb-2007, 17:13
Dear Brad, Oren, Ash, Scott, Neil

I forgot to mention I know nothing about mathematics (my teacher can back this). :-)

If I say I am clear with all your respectful answers I will be lieing.

I do a lot of fashion work so I like my standard lens to be around 40-60mm. Therefore what lens should I look out for? In inchs and in mm please.

I haven't got any lens yet. Just looking to get one. I like bokeh and possibly low contrast lens with opening of f4.5-6.8, prefer one with shutter.

Thanks a million.
Mark

Oren Grad
5-Feb-2007, 18:20
I do a lot of fashion work so I like my standard lens to be around 40-60mm. Therefore what lens should I look out for? In inchs and in mm please.

Mark - a lens in the 300-305mm or 355-360mm ranges (12 inch or 14 inch) will likely be a better match to your needs than this 10" Ektar.

styleshot
5-Feb-2007, 18:43
Oren

Thank you very much. Now I am on safe grounds. It is okay once you have the experiment with one lens but I have never used a 8x10". 4x5 yes! 6x7 yes, 6x6 yes, 35mm ahhmm yes.

I appreciate everyones input.

Pleasure being at www.largeformatphotography.info

Best Luck
Mark