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FLNightSky
professor emeritus
Reged: 03/13/06
Posts: 645
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I have a 1980's vintage 90mm Meade 97D. It takes the 0.965" eyepieces. If you're not familiar with that scope it is an MCT and you focus by twisting the OTA, like a zoom lens. It has a T-adapter for camera hookup.
My question is, if I hook up my Rebel XT (350D) to it, will the small size of the visual back cause vignetting? More generally, how can I tell if I will get vignetting on different DSLRs at prime focus?
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Falcon-
sage
Reged: 09/11/09
Posts: 242
Loc: Gambier Island, BC, Canada
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I can answer the second part of that. Nearly all DSLRs use one of two sizes of sensor (plus or minus a mm or so), so you can expect the same level of vignetting from cameras that use the same sensor size.
Most of Canon's DSLRs, such as yours, use a sensor the size of an APS-C sized film negative, while a few high end models use a larger sensor that is the same size as a 35mm film negative (aka "Full Frame").
So whatever level of vignetting you see on your 350D is going to be identical or near identical on everything from the 300D to the 1000D 7D, while the 5D and 1Ds have the larger sensor so will experience more vignetting.
All that says nothing about the other properties of the sensor of course, only the vignetting for that camera on a given telescope.
I am interested to hear how your imaging through the older scope goes.
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Tasco 11TE-5 'Lunagrosso': 4.5" Newtonian, 900mm f/7.9
Meade DS-2114S: 4.5" Newtonian, 1000mm f/8.8
Galileoscope: 50mm Achromatic Refractor, 500mm f/10
Tasco EQ-2-like mount w/ clock drive
Celestron CG-5GT mount
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ccs_hello
Post Laureate
Reged: 07/03/04
Posts: 3300
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0.965" visual back (output port) will cause physical vignetting on a APS-C sized image sensor.
Clear Skies!
ccs_hello
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FLNightSky
professor emeritus
Reged: 03/13/06
Posts: 645
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Quote:
0.965" visual back (output port) will cause physical vignetting on a APS-C sized image sensor.
Clear Skies!
ccs_hello
Thanks, I thought so.
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