Ain't that a derivative of Murphies law?
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Try YouTube. You will find more information there on this subject than you have time to watch.
This is going to be a rabbit hole if you choose to pursue it.
It is NOT as simple as putting the camera on an Equatorial mount and press the shutter release. You need a way to polar align the rig.
The longer the lens, the more accurate you’ll need to be.
Yes, these come with a PA scope; however, this will not be accurate enough. They work okay for ultra wide angle lenses on digital as you can smash up the gain on the sensor and take a heap of short (300 seconds or less) images that are then stacked in a dedicated programme to reduce signal noise.
But, that’s not what you do in LF Astro. You shoot single images. You shoot low sensitivity emulsions that suffer both reciprocity failure and colour shift. You loose light through filtration (which, unless you’re in very low Bortle skies, you will need).
So, you will need a Polar align system and a tracking system. Both will cost money and will require electric input (computer, iPad etc.)
This is NOT a pont’n’shoot pursuit....
OP, check out the Cloudy Nights forum for info on other gear that you’ll need to make it happen, aside from the camera itself.
You’re gonna love that EQ6, Corran
Attachment 213807
This is Provia 100F 4x5 shot through a Bausch & Lamb 24” f/6.3 aerial reconnaissance lens. The lens is mounted to a steel tube with a 4x5 back hacked onto it and mounted to a Losmandy dovetail for attaching to my telescope mount.
Attachment 213808
Nice! I actually have the elements for that same lens, no barrel, that I've been meaning to try mounting up and putting in front of a camera somehow. Also a 20" f/5.6 B&L as well sitting here from some estate sale in barrel - a tele lens that might be easier to use. Lots to play with.
I tried registering at Cloudy Nights some time ago and got all kinds of weird errors and problems with their forum. Not sure what's up with that.
Actually, the built in polar scopes can work just fine. I've been using a not much more than a equatorial mount, its polar scope, a modest little guide scope and a reticle eyepiece to utilize my 4x5 on the night sky for about fifteen years. I vastly prefer its simplicity and ease of use over the alternatives. You don't need a permanent pier, drift alignment, goto, laptops, pads, phones, autoguiders...
I'm posting a couple of negatives I made with little more than just that. These are on Tech Pan, and exposed recently. A nice little equatorial for tracking, polar alignment using nothing more than the built-in scope. Manual guiding. That was it. Rho Ophiuchi was done with a 300mm lens. About a twenty minute exposure. The close-up view shows how the tracking performed. The second is Orion. 180mm lens, similar exposure time, and a closeup. No alignment or tracking issues.
A bigger issue will be finding a mount that even has a polar scope anymore. I had to search hard to find a mount that still offered and used one. Most all new equatorial mounts rely on software fixes for alignment now.
20 minute subs with reticule alignment. Sorry; I don’t believe that is possible.
A 5 minute sub with tracking is tough enough with digital wide field, let alone 20 minutes unguided.
konakoa, if you can’t find a new mount with a polar scope, then you didn’t do an internet search. All the equatorial mounts on the market above “department store” level include them. Software doesn’t correct polar misalignment errors after the image is captured.
The harder part is finding them in stock... amateur astronomy has seen a huge increase in interest due to COVID driving people to find things to do at home.
Lachlan, 15+ years ago I was manually guiding 1-3 hour film shots by hand viewing through a reticled eyepiece. That was needed to correct tracking errors. This was at a very narrow FOV (1800mm focal length). When I piggybacked a camera for wide FOV shots, I didn’t need to make guiding corrections for that hour...the mount was smooth enough. For wide field shots you can get away with a barndoor tracker.
konakoa is talking about polar alignment when setting up, a different topic.
Btw, attached is a dry plate shot from a couple weeks ago, 1hr exposure, replicating a famous 1881 (iirc) dry plate photograph