newbie questions

[james morgan]

(i've posted these questions on another thread in the announcement forum... but i think it's more appropriate to ask these questions on this forum instead.)

i'm planning on getting a 4x5 to use with my canon t1i digi body to shoot artwork for repro. i'm pretty sure i can stitch 4-6 shots together to get a decent res image for a 30"x40" and fewer for smaller originals. (basically, a poor man's l/f digital back... )

anyway, before i take the plunge and start buying, i have some questions on cameras and lenses.

a) camera - i've narrowed my choices down to getting a sinar, but what's the difference between the sinar f1 and the sinar p? other than price, are the movements and dials of the f1 adequate for studio repro work? ie: smooth and fine, or would i be better off with a p?

b) movement - how much rise/fall and shifts can i get from the rear standard of a 4x5? 2-3 inches each direction? i'm not concerned about the front standard coz i would have the lens in a fixed lock-down, but i would need to be able to move and position my camera "back" about 75mm left/right and 50mm up/down to take multiple frames and stitch.

c) would a barrel lens (without shutter?) work for me? they are so much cheaper than ones with a copal. (i will use the digi's shutter)

d) focal length - my understanding is that a 4x5 focal length is roughly equivalent to 1/3 of 35mm - so a 210mm would be about the same as a 70mm. but is that the case if i attach a digi camera to the back of the 4x5 since my focal plane is now further back? would that lengthen the focal length? if so, by how much?

e) how far back would the camera have to be from a 30"x40" piece of art if i had a 210mm lens? my "studio" is kinda small...

f) lens type - i have read that using medium format lenses like the ones for mamiya rz would yield a sharper and brighter image. is that true? do i need to look into going that route, or should i start off by using an apo lens for a 4x5?

can't wait to take the plunge... and thanks for any and all input.

jimmy

[awldune]

There will be plenty of movement for what you are proposing to do, so long as the camera does have rear rise/fall and shift. I would think both of those Sinars do.

I don't think there would be any advantage to using a lens in shutter rather in barrel.

Focal length "equivalence" does not come into play since you are keeping your 1.6x crop sensor. So a 210mm LF lens gives the same field of view as a 210mm Canon EF telephoto lens when you are using the same sensor for both. It is the imaging area difference that makes the 210mm lens give a wider view on 4x5 film than on 35mm.

Mamiya RZ lens might be sharper in the middle than a LF lens of similar value, but if you are shifting 3'' you are approaching the weaker-performing edges of the Mamiya lens but are still within the optimal coverage of the LF lens.

Something to consider, your camera sensor sits 44mm behind the mount. This restricts your ability to focus lenses of a wide focal length and might also result in some vignetting as you shift. I seem to remember this is a bigger issue when using tilt/swing, which you are not proposing to do.

Simply moving and elevating the camera with a regular 35mm lens might be an easier solution. This could be facilitated by markings on your studio floor (to keep the camera at an equal distance from the work) and a tripod with a crank to elevate the center column. It might also be possible to buy or fabricate a rail to move the camera horizontally while keeping the tripod in place.

[james morgan]

thanks for your fast response...

i did fabricate a rail system to move my tripod/camera horizontally and using a crank to raise and lower the height. even so, i have slight edge discrepancies from one edge to another, making the stitching process quite annoying and cumbersome.

that's why i'm opting for the l/f with a fixed lens position (once framed) and then just shift/rise the rear standard to capture as many frames as needed of the "one" image from the fixed lens position.

on the focal length, in essence i won't be needing a 210mm or i might end up clear across the building if my subject is 30"x40"... that's good to know. and i guess the rz lens is not really of any advantage.

thanks again.

jimmy

[awldune]

Probably what you would want is a 90mm lens. To focus this with your camera attached, you will probably want a recessed lens board and a bag bellows.

[james morgan]

alright... guess i'll start making my shopping list

one more question... is it easy to mount a barrel lens to a recessed lens board?

[Lachlan 717]

alright... guess i'll start making my shopping list

one more question... is it easy to mount a barrel lens to a recessed lens board?

Depends if it a true barrel or a shutterless lens with a flange.

If it has a flange, you just need to have a hole slightly larger than the lens' diameter.

A true barrel (i.e. no flange) will pose slightly more of a challenge.

But if you're going to the trouble of making a digital back and going o the trouble of movements for stitching (rather than just shooting a piece of film and having it scanned; the method I'd use and that I would argue will provide better results), this won't be the most of your issues.

For what it's worth, here's what I'd do:

Buy the Sinar. Buy a 210mm/240mm/305mm process lens. Shoot a couple of the pieces that you want to photograph. Get them scanned. See the result. If you're not happy with the result, all that you've done is bought a film holder or two, some film and some processing.

The other thing that I would suggest is to ask the Forum nicely about borrowing/renting someone's camera, lens and film holders to do the above. Then you'll only be paying for the film and processing whilst you try analogue!!

[erie patsellis]

there's always the Betterlight approach as well.

[james morgan]

sorry, i shoulda mentioned this earlier, but budget constraints prohibit the purchase of a betterlight back... maybe later.

also, i have explored the use of film, but that, too, is too prohibitive on turnaround time. i am spoiled by the digital revolution, and have become ingrained on the rapid preview/shoot/re-shoot if needed/post processing workflow...

jimmy

[David McNiven]

Hi, Canon T1i appears to be 15 mp APS-C so 4 shots stitched gives image area 44mm. x 30mm. and approaches 60mp - minus overlaps of course - enough, I would have thought?
If my sums are correct the Mamiya RB lenses will be nowhere near their edge resolution & should be good for the purpose - their 112mm. (I think) registration distance is useful here. The 90mm. K/L might be a good choice.
Even 9 shots APS-C is only around 67x45mm. - pretty close to the designed coverage. And 135 mp!!
There are large format lenses intended for digital use but they are very expensive.
I suspect maybe even a good quality enlarging lens could give very acceptable results for copy work.
Since the front standard has to stay where it is while the rear standard is moved between shots I would definitely forget about the F/F1. I use two rear standards on mine because the normal front standard is good for nothing but a bellows joint.
I would also exclude the F2 because of its "push-pull" rise & shift - same as the F/F1 - the whole camera moves slightly no matter how careful you try to be.
My minimum specification would be: accurate, geared rise & shift on the rear standard and a rigid front standard.
I do also have a Cambo Master which has reasonably good geared movements but I think a Sinar P, or maybe an X - and one that isn't too worn - would be my ideal choice for this.
Not sure whether having "live view" (I don't) might reduce the need for a precision LF camera or whether there's a better stitching software than I've tried... but I'm looking forward to finding out!

[kbrooks]

Hi James,

Why not try one of the Canon TS-E lenses, like the 45mm or 90mm? This gives enough image circle to horizontally stitch about 3 photos (with some overlap), and you can also shift diagonally and vertically to get a few more shots to stitch. You would have an equivalent of about 50mpx then, which is probably close to what you need. I use the 24mm TS-E on a 5Dmk2 the same way to give a FOV closer to 17mm after stitching, at around 60mpx with 3 shots.

One thing I would be concerned about when using a 4x5 film lens with a resolution of 60+ megapixels would be sharpness. There is a reason they have digital LF lenses for use with digital backs, they are much sharper! You may have enough image circle, but not enough resolution on the lens. I don't know, maybe some are good enough, but it seems if the film lenses could handle it, they would make the digital ones.