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barnacle
1-Feb-2017, 14:59
I have a couple of 5x4 cameras; I have a six inch reflecting telescope. It has the usual two inch hole in the side.

How do I join part A to part B to get as large a field as possible on the film? Can anyone point me at a reference to calculate the size of the field? A 35mm or electric approach uses either a direct coupling with the image directly on the film/sensor, or an intermediate 'barlow' lens which moves the focus and provides a little magnification. I'm assuming something similar would work with the 5x4.

Neil

LabRat
1-Feb-2017, 16:56
If you are intent on LF on a telescope, the easier way is to find a LF attachment that were used for microscopes... There's a film back and a negative objective to expand the image, and can be adapted to the eyepiece tube...

But really, 35mm or digital are the tool for the job... And you will find sheet film flopping and popping around in the night air annoying unless you make up a vacuum film holder...

Steve K

Greg
1-Feb-2017, 18:13
Went in that direction with a Nikon 4x5 microscope adapter on a high quality vintage 8" Criterion telescope. The adapter took a lot of jury rigging to make stable and in the end unbalanced the telescope and compromised tracking. Low film speeds compared to my Nikon D4's very useable ISO 5000 with noise reduction... no comparison. Also tried to adapt the Nikon 4x5 microscope adapter to my Quester, and again it totally unbalanced the telescope.

barnacle
2-Feb-2017, 11:05
Okay... that looks like one to avoid then! Thanks.

Neil

tgtaylor
2-Feb-2017, 11:12
The best way to use a LF camera for astronomical photography is to piggyback off the optical tube of a motor driven telescope to capture wide angle views of the night sky. A dark sky is a must.

Thomas

Drew Bedo
5-Feb-2017, 06:23
Weight and bulk will always be challenges in mounting LF gear on a teledcope. What about working with a TravelWide body? All lightweight plastic and will take a 4x5 fiklm holder.

Randy Moe
5-Feb-2017, 11:10
Weight and bulk will always be challenges in mounting LF gear on a teledcope. What about working with a TravelWide body? All lightweight plastic and will take a 4x5 fiklm holder.

A good idea, but I don't suggest trying a Travewide in this application. Primarily as the lens/helicoid mount is not strong enough and will break, particularily when you insert and remove holders.

THe Travelwide was not made for this, it does work fine with a lightweight lens, used handheld or with the standard 1/4-20 tripod mount.

By front mounting a Travelwide to a scope all force is moved to the rather delicate internal helocoid mount.

I like my Travelwide used as designed.

tgtaylor
5-Feb-2017, 11:41
Probable the best option would be to purchase a tracking mount specifically for the camera: http://www.astropix.com/HTML/I_ASTROP/MOUNTS.HTM These will easily carry the weight of a LF camera, even a Toyo 810, but you will probably have to shield the bellows from breezes - especially with long focal lengths.

Thomas

barnacle
5-Feb-2017, 12:32
Of course, for a long exposure, an equatorial mount is required, rather than the alt/azimuth mount I actually have... otherwise the field turns in the tracked image.

Neil

Drew Bedo
7-Feb-2017, 09:48
Good points. Maybe With a supporting bracket then.