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Large format (4x5) astrophotography

Started by Tim A. , Apr 15 2008 10:10 PM
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56 replies to this topic

#1 Tim A.

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Posted 15 April 2008 - 10:10 PM

Ladies and Gentlemen :bow:,

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. :crazy:

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? :p

Tim
Colorado

#2 ZachK

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Posted 15 April 2008 - 11:30 PM

There is an article by Suk Lee on LF astrophotography. I have not done any yet but am working up to it slowly. It seems like if you have the camera and mount it would be worth a try.

#3 mlcolbert

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Posted 16 April 2008 - 02:13 AM

Tim Hi!

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!


michael

#4 Nightfly

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Posted 16 April 2008 - 05:29 AM

Kodak E200 is available in 4x5! At F/5.6 try at least 30 minutes to an hour exposure if you have dark skies.

Good Luck!

#5 AstroBobo

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Posted 16 April 2008 - 06:54 AM

Film flatness could be a problem. But try one exposure first, to decide if you need a vacuum holder.

#6 ZachK

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Posted 16 April 2008 - 11:15 PM

They make E200 in 4x5? I've never seen it, where can one get it?

#7 Nightfly

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Posted 17 April 2008 - 05:44 AM

Your right, my mistake. E200 is not available in 4x5. Too bad, that would be awesome if it was.

#8 TxStars

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Posted 17 April 2008 - 07:41 AM

Here is what you need:
http://www.freestyle...id=1303&pid=773

#9 Suk Lee

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Posted 18 April 2008 - 03:57 PM

Yes, I've done it (E100) on 4x5. The size of the transparency was just mind-boggling. I had a vacuum back but sold it.

It was an amazing way to do wide-fields, but the lenses are really really slow.

Suk

#10 Tim A.

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Posted 26 April 2008 - 04:51 PM

Suk,

Thanks for the encouragement! Your experience with 4x5 gives me some hope! :bow:

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! :shocked:

Tim
Colorado

#11 jgraham

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Posted 26 April 2008 - 05:59 PM

Way back in the late 1970's and early 1980's I did quite a bit of photography using 4x5" sheet film (mostly Tri-X) on several homebuilt cameras along with a fore-runner to the Graflex from ca. 1905 (I had to cut down 4x5 sheets to fit the metric film holder). This was a neat format to work with and was particularly well suited for patrol work. Developing the film was a bit messy; I didn't have a developing tank for sheet film so I procesed it in open trays in a dark room (I evem did roll film that way until I 'discovered' developing tanks). After a while I replaced my 4x5" film backs with a Polaroid film back (cut from a camera I picked up at a garage sale) which let me use ASA 3000 speed b&w self-developing film. Now that was an interesting (if grainy) format to work with.

#12 Suk Lee

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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.

Cheers,
Suk

#13 ZachK

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Posted 27 April 2008 - 02:20 PM

I am hoping to do some LF astro work, I have a bunch of extra film holders and plan to convert 2-5 of them to vacuum backs. (Yea for cheap film holders from Ebay). That will probably be for 2009, for '08 I will stick to 35mm and 120 format. If nothing else on the 35mm I can get a pretty good shot at 2-3 minutes which is what the mount I am working on will probably be able to do. (Fork mount on a eq-platform, if I can ever get it built)

#14 Tim A.

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Posted 09 May 2008 - 12:11 AM

I thought a little bit about how to convert a standard 4x5 film holder into a vacuum unit, but I haven't come up with a good design.

It seems like it should be possible, and I'm curious about how you plan do it.

-- Tim

#15 ZachK

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Posted 09 May 2008 - 03:57 AM

Check out this link http://www.magnachrom.com/MCHome.php they had plans in issue #5

#16 Achernar

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Posted 27 May 2008 - 10:44 PM

I used to develop 4x5 sheet film all the time in trays. It was easy to so and as long as I first presoaked the film in a tray of water first and kept the emulsion side down, I never had scratching problems in the hard rubber trays I used. They have very slick and smooth bottoms and keeping the temperature of the chemicals around 68 degrees helped a lot preventing the emulsion from getting too soft and easily damaged. The film I developed most of the time was you guessed it, Tri-X. I think it was one of the best black and white films ever made, at least for general photography. It worked for me fairly well for astro photography either, considering the fact it was never intended for it. As for trying astrophotography with a 4x5 camera, I did once and found one major problem to watch out for, the film bowing or shifting in the holder. It recorded light just fine, but every shot I made was ruined because the film slumped in the holder and the center of the negatives were badly out of focus. Your lens can dew over, which also ruins your shots, so you will want a dew cap and heater strip to keep the lens from fogging up. Also, at F/12, you will have some insanely long exposure times, but then again you won't be fogging the film from sky glow unless you expose for an hour or longer. Unless that is, a light shines right into the lens, in which case your picture is ruined and you will have to take it again.

Taras

#17 rlc

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Posted 08 June 2008 - 07:41 AM

Wonderfully pleased to stumble onto this group. I have been, off and on, fooling with 4x5 film work for years. Had this material been available I would have made much more progress.
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.

Bob Clark

#18 Nightfly

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Posted 08 June 2008 - 09:46 AM

It would be interesting to see what you come out with. Medium and large formats are the final frontier for film. Good to have another analog man with us.

Jim

#19 tommyhawk13

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Posted 10 June 2008 - 11:58 AM

I have read that Kodak E100G was probably the best color transparency 4x5 film available.
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?

#20 Nightfly

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Posted 10 June 2008 - 12:06 PM

Provia 100F is the best star trail film available. Great for long exposures at moderate apertures in that aplication.
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.

Jim

#21 Tim A.

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Posted 21 October 2008 - 10:43 PM

For anyone interested, I came across this page which details exactly how to build your own vacuum back. So far, I've got the vacuum pump working. Next up: build the back.

http://www.deadbread...crumbs/vac.html

-- Tim
Colorado

#22 ZachK

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Posted 22 October 2008 - 09:36 AM

At some point I was planning to convert 2-3 of my film holders to vacuum backs. I just need to find the plastic and some time.

#23 Nebhunter

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Posted 23 October 2008 - 08:00 PM

It's great to see a group interested in this area. Go for it guys. We are "The Last of the Emulsions". Keep a tradition alive.

Igor

#24 tommyhawk13

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Posted 23 October 2008 - 08:48 PM

Aside from the weight of the camera, the tendancy for its components to shift, and keeping the film flat, there are many other issues to deal with.

- Film
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.

-Lenses:
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.

#25 Kona

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Posted 23 October 2008 - 09:08 PM

I'm the author of the webpage posted above. The biggest problem of them all is wind in the bellows of the camera. Second is getting/keeping the telescope mount precisely polar aligned (I use a GEM mount).

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.
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