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Pages: 1 | 2 | 3 | (show all) Tim A. scholastic sledgehammer Reged: 09/19/07 Loc: 40 30'N 105 3'W Re: Large format (4x5) astrophotography [Re: Nightfly]       #2711656 - 10/21/08 11:43 PM Edit   Reply   Quote Quick Reply   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.com/crumbs/vac.html -- Tim Colorado Post Extras:       ZachK professor emeritus Reged: 08/21/05 Loc: Israel Re: Large format (4x5) astrophotography [Re: Tim A.]       #2712128 - 10/22/08 10:36 AM Edit   Reply   Quote Quick Reply   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. Post Extras:       Nebhunter Carpal Tunnel Reged: 10/04/03 Loc: Frostbite Falls Re: Large format (4x5) astrophotography [Re: Tim A.]       #2715114 - 10/23/08 09:00 PM Edit   Reply   Quote Quick Reply   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 Post Extras:       tommyhawk13 scholastic sledgehammer Reged: 09/28/07 Loc: Jacksonville, Fl Re: Large format (4x5) astrophotography [Re: Nebhunter]       #2715196 - 10/23/08 09:48 PM Edit   Reply   Quote Quick Reply   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. Post Extras:       Kona member Reged: 10/22/08 Re: Large format (4x5) astrophotography [Re: tommyhawk13]       #2715224 - 10/23/08 10:08 PM Edit   Reply   Quote Quick Reply   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. Post Extras:       Mopman sage Reged: 10/14/06 Loc: Richland, WA, USA Re: Large format (4x5) astrophotography [Re: Kona]       #2715875 - 10/24/08 11:16 AM Edit   Reply   Quote Quick Reply   Hi Danny, Welcome to CloudyNights! I really enjoyed looking at you web site; lots of nice images and good info Could you explain "wind in the bellows of the camera" to me? Thanks! Gary Post Extras:       tommyhawk13 scholastic sledgehammer Reged: 09/28/07 Loc: Jacksonville, Fl Re: Large format (4x5) astrophotography [Re: Kona]       #2715922 - 10/24/08 11:42 AM Edit   Reply   Quote Quick Reply   Danny, what film and lens are you using? Post Extras:       Achernar Postmaster Reged: 02/25/06 Loc: Mobile, Alabama, USA Re: Large format (4x5) astrophotography [Re: tommyhawk13]       #2716352 - 10/24/08 03:59 PM Edit   Reply   Quote Quick Reply   I once tried to shoot star trails with an old 4x5-inch press camera that had a 150mm lens on it. To my chagrin, the moment I turned on the light after they were in the Rapid Fixer for a few minutes, I saw big trouble. Every one of the negatives showed the film buckled in the holder rendering the middle blurry and the edges sharp. They were useless, while the ones I took with my 35mm Nikon turned out perfectly. The film holders work great for normal photography and I enjoyed using a large format camera immensely. However, they don't hold the film flat enough in my experience. I rarely used the lens wide open on that press camera, typically I used it stopped all the way down for the work I did with it. But I would sooner use a 120 roll-film camera such as an old Yashicamat 124 or Rollei twin-lens reflex before I would use a view camera. Trying to find film good for astrophotography is bad enough for 35mm cameras, I can't imagine it's any better for a large format camera. Taras Post Extras:       Tim A. scholastic sledgehammer Reged: 09/19/07 Loc: 40 30'N 105 3'W Re: Large format (4x5) astrophotography [Re: Kona]       #2716450 - 10/24/08 05:18 PM Attachment (94 downloads) Edit   Reply   Quote Quick Reply   Quote: I'm the author of the webpage posted above. First, thanks so much for the informative web site. I wouldn't have thought to re-engineer an aquarium air pump to make it a low-pressure vacuum pump! Quote: 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). This is a photo of my vintage Linhof aerial camera. The lens is a Schneider-Kreuznach Symmar 180mm f/5.6 in a Linhof shutter. Focus is permanently set for infinity, and the cast body was designed for this lens. It weighs about seven pounds (2 kg), and will ride on a CG-5 GT mount. Excepting the shutter, this camera has no adjustments. With a vacuum back, I should be good to go from a mechanical perspective, though I do expect to shoot at f/8. The film is something I'll have to deal with. Hey, tommyhawk, what is this Rollei film you mentioned? Another possibility is to shoot on fast B&W film using RGB filters, and then digitally stack the results for color rendering. But I'd prefer to stay analog from end to end. So I may just go B&W. Honestly, I've seen some wonderful B&W images. In some respects B&W is more "natural" than color, which the eye can never see in these things anyway. -- Tim Post Extras:       tommyhawk13 scholastic sledgehammer Reged: 09/28/07 Loc: Jacksonville, Fl Re: Large format (4x5) astrophotography [Re: Tim A.]       #2716484 - 10/24/08 05:50 PM Edit   Reply   Quote Quick Reply   Hey Tim, there is a buzz about a new black and white film Rollei made that replaces Tech Pan Rollei film I can't find any information on reciprocity failure, and I'm assuming that everyone used to Hyper the old Kodak Tech Pan. Post Extras:       Tim A. scholastic sledgehammer Reged: 09/19/07 Loc: 40 30'N 105 3'W Re: Large format (4x5) astrophotography [Re: tommyhawk13]       #2716591 - 10/24/08 06:57 PM Edit   Reply   Quote Quick Reply   Interesting. I wish they had it in 4x5. I used Kodak's Tech Pan for large-format landscapes for years. At ISO 32, the Rollei film would make for some looong astrophoto exposures! Post Extras:       Kona member Reged: 10/22/08 Re: Large format (4x5) astrophotography [Re: Tim A.]       #2716842 - 10/24/08 10:04 PM Edit   Reply   Quote Quick Reply   Thanks for the welcome. I'm a long time lurker; just never had anything to add that hasn't been said before. Mopman: Could you explain "wind in the bellows of the camera" to me? Most all large format cameras have a pleated flexible bellows that connect the lens board to the film back. (Tim's got an exception!) The bellows can be quite large. Mine are 6" square and can extend out to 16". Depending on the focal length of the lens being used, a good bit of the bellows are racked out to reach infinity focus. Any slight breezes in the night catch the bellows like a sail. It's not so much that a breeze wobbles the camera, but more my telescope mount. The R.A. axis on my telescope mount has a tiny amount of play. It's not typically a problem as I guide out any errors manually with a guide scope -- but if a sudden gust comes along, the force goes straight through the camera and into the telescope mount. I literally see the stars jump in my guide scope when the teeth and worm gear of my mount wiggle. However as long as it's a calm, still night all usually goes well. tommyhawk13: what film and lens are you using? I use a variety of lenses from 90mm f/4.5 (wide angle) 150mm f/5.6 (normal), a 300mm f/5.6 (mild telephoto) and a 400mm f/5.6 (telephoto). Typically I use the telephotos wide open and the wide angle stopped down to f/8 to correct aberrations in the corners of the frame. I've used Fuji Provia 100F and Kodak E100G. Both work pretty well. When I tested the two films I made identical shots with both films and repeated the test for several parts of the sky. When I compared the finished films side by side I preferred E100G for its slightly better color. E100G is what I use now. Post Extras:       jrw11 professor emeritus Reged: 06/09/07 Loc: unknown Re: Large format (4x5) astrophotography [Re: Kona]       #2717077 - 10/25/08 01:46 AM Edit   Reply   Quote Quick Reply   For me a big problem with a view camera would be in focusing. With a camera such as a Graphic, they have infinity stops. But, a monorail doesn't have that. Mine sure doesn't. Post Extras:       tommyhawk13 scholastic sledgehammer Reged: 09/28/07 Loc: Jacksonville, Fl Re: Large format (4x5) astrophotography [Re: Tim A.]       #2717166 - 10/25/08 06:23 AM Edit   Reply   Quote Quick Reply   Quote: Interesting. I wish they had it in 4x5. I used Kodak's Tech Pan for large-format landscapes for years. At ISO 32, the Rollei film would make for some looong astrophoto exposures! My bad, I assumed it was available in sheets. Post Extras:       Mopman sage Reged: 10/14/06 Loc: Richland, WA, USA Re: Large format (4x5) astrophotography [Re: tommyhawk13]       #2719067 - 10/26/08 02:23 PM Edit   Reply   Quote Quick Reply   "My bad, I assumed it was available in sheets." I believe it is available as sheet. Mopman Post Extras:       Greyhoundman sage Reged: 11/20/07 Re: Large format (4x5) astrophotography [Re: Mopman]       #2719085 - 10/26/08 02:35 PM Edit   Reply   Quote Quick Reply   Rollei iso 25. 4X5 sheets at Freestyle Photographic supply. http://www.freestylephoto.biz/sc_main.php?cat_id=0 Edited by Greyhoundman (10/26/08 02:36 PM) Post Extras:       GilATM super member Reged: 08/04/07 Re: Large format (4x5) astrophotography [Re: Greyhoundman]       #2783406 - 12/03/08 01:47 AM Edit   Reply   Quote Quick Reply   I would suggest you first simply try a couple of shots - one at 30 min. and one at 1 hr. - try a section of the milky way. If the film seems loose when you load it, I would use a bit of tape to keep it from sliding around during the long exposure. If the results show coma at the edges - I would simply make a cardboard ring to reduce the aperture. Take some pics! Have some fun! - Gil Post Extras:       erie patsellis journeyman Reged: 09/13/08 Re: Large format (4x5) astrophotography [Re: Nightfly]       #2817566 - 12/21/08 11:50 AM Edit   Reply   Quote Quick Reply   Tim, how are you making out with this? I"ve been building an 8x10 fixed focus camera, just trying to hunt down a 6" aero ektar (178mm f2.5) at a reasonable price to make it workable. The vacuum back is the easiet part, I'm still trying to wrap my head around the mount/drive issues. I haven't been involved in astonomy since HS (late 70's). Post Extras:       Tim A. scholastic sledgehammer Reged: 09/19/07 Loc: 40 30'N 105 3'W Re: Large format (4x5) astrophotography [Re: erie patsellis]       #2844315 - 01/05/09 01:24 AM Edit   Reply   Quote Quick Reply   Slow ... I have too many projects and too much laziness for fast progress on anything, it seems. I've got the vacuum pump working; that was a snap. I have yet to build the vacuum film holder. It doesn't seem like it should be too hard once I get around to it. Then I'll have to rig a way to attach it to my CG5-GT mount. I had originally planned to piggy-back it on the 6" refractor, but this old aerial camera is pretty heavy and I think the combination would be too much for that mount. Good luck finding that Aero-Ektar. Never heard of 'em myself. Sounds like a pretty big hunk of glass! And I am much impressed that you'd build a fixed-focus 8x10. That's ambition! As for the mount, well, you might be able to pick up a good equatorial drive in the classifieds here for a reasonable price; I got mine off Craig's List. Then you (like I) need to rig a dovetail adapter to strap that big camera onto it, something that lets you swivel the camera to the proper orientation after it's pointed at your target. Aye, there's the rub. Are we having fun yet? Post Extras:       erie patsellis journeyman Reged: 09/13/08 Re: Large format (4x5) astrophotography [Re: Tim A.]       #2844575 - 01/05/09 08:09 AM Edit   Reply   Quote Quick Reply   Oh, a fixed focus is easy, I"ve built a traditional 8x10 field camera, as well as a 20x24, so a light tight box should be easy. erie Post Extras:       Pages: 1 | 2 | 3 | (show all)

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