Shadowalker
Apocaloptimist
Reged: 11/23/04
Posts: 10857
Loc: Carriere, Mississippi, USA
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Just for the heck of it, I put in 1.5 and 2.0 X barlows and went over to mars. Focused and took 30 images. This is the result in registax.
I took much better planets with my old Nikon 990 using afocal projection. So how do we make planetares better using prime focus? I have a 5X barlow. Something like that?
The EFL would have been 3000mm. The image is so small relative to the picture area. Does this mean I need 5000 or more EFL? Anyway, I need to re-train myself on planets.
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"The truth rarely gets in the way of a good story. ~ R. Woods
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Rat8bug
Carpal Tunnel
Reged: 01/07/05
Posts: 1713
Loc: Michigan
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For Mars, something on the order of f/40 to f/50 is wbat you should be using. With an f/5 Newt, that is hard to get except with EP projection. You are right, afocal is easier, because of the zoom feature of the camera. If you had an f/10 SCT, then it wuld be easy using a 4x Powermate to get f/40 at prime focus. That is why I kept my Nikon 4500 for the planets and moon. The DSLR for DSOs....
http://www.barrie-tao.com/astro_photo.html
Ciao...Barry
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Nikon D40/D50/D70 DSLR
WO 105mm Triplet APO
WO Zenithstar 66SD APO (Black 'n Blue)
WO 8 x 45mm APO Bino
UO 20 x 80mm Bino
Vixen 80SS Refractor
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bill w
Postmaster
Reged: 03/26/05
Posts: 10277
Loc: southern california
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if you don't have the barlows
can't you do eyepiece projection
with a high power EP and a DSLR?
the other things folks have talked about is mirror lock up
and short exposure time
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-bill w
nexstar 8 GPS
canon 300D, Toucam Pro II
SXV-H9C, H9, SX Lodestar autoguider, SX-AO, DMK 51
FS 102 (OLV), FS60 CSV, 8" LX200R, Lunt 60/50 double stacked PT B1200, Losmandy G 11, ASA DDM60
http://astro.whwiii.net/
image processing monitor calibrated to just differentiate darkest boxes:
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Shadowalker
Apocaloptimist
Reged: 11/23/04
Posts: 10857
Loc: Carriere, Mississippi, USA
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Well, I have a bunch of barlows... 1.5, 2, 2.5, 3 and 5.. and those are just my good ones 
When it clears agin, I'll try my 5x barlow.. 10,000mm efl at F25. geez. And then to F40? I'll give it a shot.
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"The truth rarely gets in the way of a good story. ~ R. Woods
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jrcrilly
Refractor wienie no more
Reged: 04/30/03
Posts: 30716
Loc: NE Ohio
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Quote:
Well, I have a bunch of barlows... 1.5, 2, 2.5, 3 and 5.. and those are just my good ones
When it clears agin, I'll try my 5x barlow.. 10,000mm efl at F25. geez. And then to F40? I'll give it a shot.
I don't think you'll like shooting at 10,000mm (though that would require an F ratio of 50 rather than 25). I don't remember ever seeing anyone shoot at over 8000mm focal length. It's the focal length that both determines image scale and runs you into the seeing limits. The rules of thumb for F ratio seen mentioned in various places are appropriate only for smaller instruments. Use whatever F ratio it takes to get the focal length you need. With my seeing here, 5000mm is about the limit.
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John C
Battle Cry of Reno
http://www.wadsworthobservatory.com
My Cloudy Nights gallery
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Shadowalker
Apocaloptimist
Reged: 11/23/04
Posts: 10857
Loc: Carriere, Mississippi, USA
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Thanks, John. That makes sense. Focal ratio establishes the sensitivity to light and focal length establishes the magnification. And you're right - I did the calc quickly in my head and made a mistake. At 5X with my 200mm F5, I get 5000mm, not 10K. The image I took was at 3000mm. I doubt seeing will support much higher magnification than I'd get at 5000mm.
I do have some nice EPs, though. And I haven't used them in a good while! Maybe I need to get them out and do some afocal as Mars gets closer.
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"The truth rarely gets in the way of a good story. ~ R. Woods
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Shadowalker
Apocaloptimist
Reged: 11/23/04
Posts: 10857
Loc: Carriere, Mississippi, USA
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One more thing.. I have a gazillion images of Jupiter and Saturn, but this was my first of Mars.
which reminds me. While I'm at it, why not go for Uranus and Neptune? Well placed, it's a good time. I'd be satisfied with blue or green dots
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"The truth rarely gets in the way of a good story. ~ R. Woods
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jrcrilly
Refractor wienie no more
Reged: 04/30/03
Posts: 30716
Loc: NE Ohio
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Quote:
One more thing.. I have a gazillion images of Jupiter and Saturn, but this was my first of Mars.
which reminds me. While I'm at it, why not go for Uranus and Neptune? Well placed, it's a good time. I'd be satisfied with blue or green dots
Mars is still pretty small; it'll be much easier to get reasonable image scale in a month or two.
You should be able to get very nice blue and green discs from the outer gas giants - we'll look forward to seeing those shots.
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John C
Battle Cry of Reno
http://www.wadsworthobservatory.com
My Cloudy Nights gallery
AT12RC
AT65EDQ
QSI683WSG-8
Roper Scientific Quantix 6303E "project" camera
mystery EQ mount on the way
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jrcrilly
Refractor wienie no more
Reged: 04/30/03
Posts: 30716
Loc: NE Ohio
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Quote:
I do have some nice EPs, though. And I haven't used them in a good while! Maybe I need to get them out and do some afocal as Mars gets closer.
I actually dug my EP case out last weekend, went to a dark site, and spent a night looking through telescopes for a change - it was kind of nice.
If the weather permits we have a public thing at our Club site this weekend so I may get to do it again (though our site has been very poor this season).
I suspect that with an assortment of multipliers such as yours you'll do better to use them rather than EP projection; the maximum usable image scale will be the same either way.
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John C
Battle Cry of Reno
http://www.wadsworthobservatory.com
My Cloudy Nights gallery
AT12RC
AT65EDQ
QSI683WSG-8
Roper Scientific Quantix 6303E "project" camera
mystery EQ mount on the way
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glacy31
sage
Reged: 05/31/05
Posts: 339
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So do you guys advise getting my coolpix 990 setup for planets? and using EP stuff or going prime focus with a webcam and stacking aplenty.
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Losmandy G11 Gemini
TMB 80/480
WO FLT 110
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jrcrilly
Refractor wienie no more
Reged: 04/30/03
Posts: 30716
Loc: NE Ohio
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Quote:
prime focus with a webcam and stacking aplenty.
That sounds like the formula for succesful planet imaging to me.
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John C
Battle Cry of Reno
http://www.wadsworthobservatory.com
My Cloudy Nights gallery
AT12RC
AT65EDQ
QSI683WSG-8
Roper Scientific Quantix 6303E "project" camera
mystery EQ mount on the way
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glacy31
sage
Reged: 05/31/05
Posts: 339
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Just need another barlow, doesnt need to be a 2" AP though.
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Losmandy G11 Gemini
TMB 80/480
WO FLT 110
EOS350DH
ST 7i
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Oldfield
Postmaster
Reged: 03/20/02
Posts: 6310
Loc: Hong Kong
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for mars, f/50 is do-able. I've some but definitely seeing was the limit... the amount of detail is just like f/30 which is my favorite for mars.
f/50 or actually, it should be ~f/57 was done with a C8 with a 5x powermate...
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The Home Astronomer from a city where most people are proud of the light pollution
Toys: Tele Vue Ranger, GOTO Mark-X, Lumenera LU070M, Canon 10x30 IS...
My observation log and ideas My General Blog
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Shadowalker
Apocaloptimist
Reged: 11/23/04
Posts: 10857
Loc: Carriere, Mississippi, USA
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I haven't tried the webcam route yet. But I did use my 990 a lot for lunar and planetary. Nice thing about it was I didn't need a computer to use it. But the Nikon remote was a necessary addition.
If you do use it, I recommend the scopetronix EP/camera adapter. It comes in either 14 or 18mm FL and the eye side is threaded for 28mm filter fitting on the nikon. Very easy to use. It was easy to pop off a hundred images. USing Registax I got pretty good results.
I sold my Nikon to get the D-Reb. I don't regret it, but the D-Reb takes a lot longer to acquire 100 images. The web cam can be set to record an AVI video and acquire a lot faster.
I'll probably fire up my LPI I use for autoguiding for some martian images.
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"The truth rarely gets in the way of a good story. ~ R. Woods
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markf
Carpal Tunnel
Reged: 10/13/04
Posts: 1936
Loc: Houston, TX
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Quote:
Quote:
prime focus with a webcam and stacking aplenty.
That sounds like the formula for succesful planet imaging to me.
Actually, unless you have a long focal length scope, you'll still need to use barlows for webcam imaging
Webcams have the advantage of getting considerably more frames to work with; better odds to beat the seeing . I myself have never gone much over 3000mm focal length.
Mark
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Celestron C6N on a CG5-GT
Orion 80mm Refractor (guidescope)
ToUCam Pro II
Canon 40D
http://www.carsandfish.com/astroweb
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Shadowalker
Apocaloptimist
Reged: 11/23/04
Posts: 10857
Loc: Carriere, Mississippi, USA
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Mark,
that image was at 3000mm FL. I'm sure I can get some more out of it. But the image is still tiny. I'm certain I need to push the FL some more to get detail. But good grief, the DSLR frame is huge! If I have time this weekend I'll experiment with some other configurations.
What the D-Reb needs is a high-res/fine image type but a cropped frame for planetary. That would be nice!
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"The truth rarely gets in the way of a good story. ~ R. Woods
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jrcrilly
Refractor wienie no more
Reged: 04/30/03
Posts: 30716
Loc: NE Ohio
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Quote:
What the D-Reb needs is a high-res/fine image type but a cropped frame for planetary. That would be nice!
You can do that now. The pixel size of the DSLR is similar to that of the webcams; just crop a webcam-sized chunk from the center.
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John C
Battle Cry of Reno
http://www.wadsworthobservatory.com
My Cloudy Nights gallery
AT12RC
AT65EDQ
QSI683WSG-8
Roper Scientific Quantix 6303E "project" camera
mystery EQ mount on the way
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Shadowalker
Apocaloptimist
Reged: 11/23/04
Posts: 10857
Loc: Carriere, Mississippi, USA
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Quote:
Quote:
What the D-Reb needs is a high-res/fine image type but a cropped frame for planetary. That would be nice!
You can do that now. The pixel size of the DSLR is similar to that of the webcams; just crop a webcam-sized chunk from the center.
Can it be done automatically within the camera? I'd hate to have to do it to 50 or 60 individual files post acquisition. Also, a cropped image would D/L from the camera much faster (assuming it can do it).
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"The truth rarely gets in the way of a good story. ~ R. Woods
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markf
Carpal Tunnel
Reged: 10/13/04
Posts: 1936
Loc: Houston, TX
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Your scale is very close to the Toucam, so the pixels are about the same size. I think the D-Reb's pixels are a bit smaller, but not by much.
Here's my Mars at 3000mm with the Toucam. Given good seeing, you can push it to 5000mm or a little more, but in any case, it's never gonna take up much of the FOV on the Rebel's chip. Even with the 640x480 image of the webcam, i still crop a bit. Just stack and do all your processing first, then crop it. Doesn't help with the downloads, though 
Mark
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Celestron C6N on a CG5-GT
Orion 80mm Refractor (guidescope)
ToUCam Pro II
Canon 40D
http://www.carsandfish.com/astroweb
Edited by markf (08/11/05 05:16 PM)
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jrcrilly
Refractor wienie no more
Reged: 04/30/03
Posts: 30716
Loc: NE Ohio
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Quote:
Can it be done automatically within the camera? I'd hate to have to do it to 50 or 60 individual files post acquisition. Also, a cropped image would D/L from the camera much faster (assuming it can do it).
I know that Images Plus can crop a batch of files as one operation but that doesn't help with download speed. I'm pretty sure that Images Plus somehow loads only a subframe in focus mode but I don't know whether there's a way to save those subframes.
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John C
Battle Cry of Reno
http://www.wadsworthobservatory.com
My Cloudy Nights gallery
AT12RC
AT65EDQ
QSI683WSG-8
Roper Scientific Quantix 6303E "project" camera
mystery EQ mount on the way
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