Large format (4x5) astrophotography
Posted 15 April 2008 - 10:10 PM
I'm about to embark on a large challenge for which I am ill-prepared, and I can use all the help I can get.
I have landed a top quality 4x5 aerial camera. It has no adjustments beyond exposure. That is, the focused is fixed at infinity, and it has none of the "usual" 4x5 camera movements. It is, basically, a brick with a lens.
Oh, and a fine lens it is. A Schneider convertible, at 150mm f/5.6 and 265mm f/12 (I think), depending on how you configure it. This is a sharp, contrasty, fast large-format lens. Mounted in a brick.
OK. So. I intend to lash this puppy to a motorized Celestron CG5 mount to take some, um, shall we say "very long exposure" wide-field astronomical photographs of (one would hope) top quality. I have all the incidental necessaries, like film holders, due to my alternative expensive habit, which is large-format photography.
But (and unlike my own, it's a very big but): I am a brash beginner in this. I have never tried astrophotography of any kind, much less of the large-format kind.
I can foresee so many issues. Some I am confident about managing (like, say, polar alignment). Others I'm not so sure about.
It would seem that reciprocity failure would be a huge issue. Likewise (and partly due to reciprocity), film choice must be crucial. There must be scads of other "gotcha"s lurking about.
And I'm a neophyte, a newbie, a sophomore with Ph.D. dreams.
First: Has anyone you know ever tried 4x5 astrophotography? Have you? If so, that person (you?) is the person I need as a mentor. If not ... dang. Well, if not, whatever advice you film astrophotographers have to offer will be gratefully accepted.
And really, how many times in your life is your advice really welcome?
Posted 15 April 2008 - 11:30 PM
Posted 16 April 2008 - 02:13 AM
like you, another novice, I will be working with film and plate glass, in a lunar and planetary camera and experimenting with using a 4x5 body as well. They will soon be attached to a 130. Looks like we will haveto chase up Zach's suggestion re Suk Lee's article. Keep in touch!
Posted 16 April 2008 - 05:29 AM
Posted 16 April 2008 - 06:54 AM
Posted 16 April 2008 - 11:15 PM
Posted 17 April 2008 - 05:44 AM
Posted 18 April 2008 - 03:57 PM
It was an amazing way to do wide-fields, but the lenses are really really slow.
Posted 26 April 2008 - 04:51 PM
Thanks for the encouragement! Your experience with 4x5 gives me some hope!
When I came across a 1950's vintage Linhof 4x5 aerial camera, I couldn't pass it up. It has a 180mm f/5.6 Symmar lens in a Linhof shutter. It will at least be a good counterweight on my 6" refractor, to help get me off my knees when I'm using the beast.
Anyway, I should probably stop that Symmar down to at least f/8. Some refractors in use for astrophotography are near that focal ratio, which makes me think it's an aperture I can work with.
Given f/8 and E100 film, I'm trying to guess some trial exposures. Any starting points you could suggest on that front? Most film astrophotographers aren't using E100, which sort of leaves me in the dark (no pun intended).
You had mentioned you used a vacuum back. Do you think that's essential? Obviously, if the film shifts during the exposure, that would be a bad thing. But I think it's unlikely I can find a vacuum back, so I may just have to think of a way to wedge a sheet of film in a regular holder in such a way that it won't move.
I don't think film buckling should be a big issue, unless E100 has a really thin base. I work and live in a generally very dry climate, so humidity is not an issue.
Any other advice you might have would be much appreciated! I'm excited to give this a try, and I hope to not burn through too much $$$ film in my learning curve!
Posted 26 April 2008 - 05:59 PM
Posted 27 April 2008 - 03:13 AM
But I think it's unlikely I can find a vacuum back, so I may just have to think of a way to wedge a sheet of film in a regular holder in such a way that it won't move.
I tried a shot without a vacuum back, and got a soggy out-of-focus mess in a 20 minute exposure. However, it gets pretty damp where I am at night, so I had no choice.
Your mileage may vary!
At f8 you can probably start with 10 minutes and easily go to 40 without running into sky-fog issues. At 40 minutes if you get short streaks instead of pin-points, it could be your frame shifting - 4x5 cameras aren't made to be held at the funny and shifting angles of long-exposure photography. I never had a problem with that but my Linhof is built like a tank.
Posted 27 April 2008 - 02:20 PM
Posted 09 May 2008 - 12:11 AM
It seems like it should be possible, and I'm curious about how you plan do it.
Posted 27 May 2008 - 10:44 PM
Posted 08 June 2008 - 07:41 AM
Recently move from a moderately poor sky area to a moderately good sky area. Have set-up pull down tarps to shield local ambient light and a concrete topped table for the mount. (Pretty good barn door).
Have been using TMAX 400 film. I suspect that may be a mistake. My home made camera is abt 8 inch fl and f5.6. Images are pretty good over most of the film but, at the edges, there is some coma. My exposure limit seems to be about 20 mins. I think I am being limited by rec limit. I intend to try a different film (what?) and going down to abt f8-9. (Different expiriments). I'll report to this group re what, if anything, I learn.
Posted 08 June 2008 - 09:46 AM
Posted 10 June 2008 - 11:58 AM
Finding a fast lens would probably be the most important ingredient.
I have tried to compare films by reciprocity charts, but they don't take into account the real long exposure times.
Fuji Provia 100F looks good on paper, and so does Kodak E100VS, but how do they perform at about an hour?
Posted 10 June 2008 - 12:06 PM
For recording lots of detail in wide field piggyback work it is best with fast apertures, perhaps f/2.8 or faster. I've exposed it for over a half hour at f/4 and recorded only about as much as what E200 records in 10 minutes.
Posted 22 October 2008 - 09:36 AM
Posted 23 October 2008 - 08:00 PM
Posted 23 October 2008 - 08:48 PM
Kodak does not make E-200 in sheet film, and Fuji certainly doesn't make a 400 speed sheet, and Tech-pan is extinct. Kodak does make E-100 in sheet film, but it needs a much longer exposure.
There aren't many large format lenses that are fast.
Prime lenses are typically stopped down at least 1 step to keep the images in the corners sharp. Most of the affordable "fast" LF lenses are f/5.6, so we should shoot at f/8?
Combine that focal ratio and a slower film, and an attempt to shoot the North America nebula might take 2 hours or more to get good detail.
I wonder if this new Rolleii film could come into play.
There are fast, cheap lenses out there that were made for press cameras, and as fast as f/2.8. These may not cover
4X5 at infinity, and they may have more coma.
Posted 23 October 2008 - 09:08 PM
The magnification with large format lenses is a bit more than what most of us are used to, i.e. smaller 35mm cameras. You really have to handle a large format camera as you would a long telescope optic.
The rest is very manageable.