Posts Made By: John Boudreau

Well, I may have missed some--- but I haven't yet come across a telescopic film image of Mars on this forum. So I figure'd I'd throw mine in .

A couple of weeks ago in between recording webcam videos of Mars through my C11, I shot a roll of what is currently the finest-grained color slide film available, the newly released Fuji Astia 100F. I scanned the best 18 frames at 2700 dpi and saved them as BMP files, and processed them in RegiStax2. Additional processing was done in Photoshop 6 and grain reduction in Neat Image. Eyepiece projection was used for the C11 yielding about f/50, exposures were "hat tricked" at about 1/3 of a second. Camera was an OM-1n.

I've also put up a webpage with a comparison of the film and webcam result I got that night:
http://home.comcast.net/~jeboud/film_mars.htm

Actually, some of the very best individual film frames were reasonably close to the stacked result. The greatest advantage of stacking was grain reduction.

John Boudreau
http://home.comcast.net/~jeboud/astro.htm

Here's a near-IR result from 4 separate videos taken back on June 17th--- during one of the rare periods in June when it wasn't raining here in New England!

One of the great things about imaging Mercury is that it rotates so slowly that the best frames from videos taken over a period of a couple of hours can be used to make a processed image. The UT reported here is an average of the times involved during a span of about 1 hour and 12 minutes, during this time Mercury's CM changed by only about .24°!

--- John

Hi Don,

With the setup your using you won't be able to record Mars at any more than a fraction of a millimeter across at the film plane. So you won't be getting much detail--- but I suppose it's possible to *just* capture the polar cap. You'd probably need an effective focal length of 3000mm or more to make it worthwhile.

You didn't mention the film your using,you would need to get as fine-grained film as possible for such a small image on film as Mars, and that means slide film like Fuji Provia 100F, either the new Velvia 100F or Astia 100F, or the Kodak E100 films. Even the finest grained color print films can't come close to competing with these. But if B&W print is OK, then Kodak Tech Pan would work fine.

The exposures you attempted were _way_ too long. Even with the relatively slow 100-speed films I've mentioned, exposures will range around 1/60 to 1/30 sec with the setup your using. If you boost the scope up to f/50 or so with eyepiece projection, then your in the 1/4 to 1/2 second range.

If at all possible, it would be far better to use a digital camera afocally, or a webcam with your barlow.

John Boudreau
http://home.comcast.net/~jeboud/astro.htm

Hi Randy,

I've modified a Lumicon NEG and the TV85 flattener's 2" chromed barrel for OA guiding my TV85. But these modifications will only work with a TV85 with the older thumbscrew type retainer, not the compression ring type. The compression ring unit adds too much length to the focus tube, robbing critical "in" focus travel for this setup.

Is your scope a thumbscrew or compression ring type?

I can post a picture of it if you're interested.

John Boudreau
http://home.comcast.net/~jeboud/astro.htm

While a fine focuser is an advantage, many a fine image have been taken through small refractors over the years without one. I wouldn't worry about using the stock focuser.

What I would suggest is that you practice daytime focusing instead of focusing on a star the night before. If the daytime temperatures are even a few degrees different than at night, your focus point is definitely going to differ--- in fact even if the air temperatures are about the same the fact that the scope will be in direct sunlight will warm up the metal tube and cause some expansion. It will be most noticeable with the TV76 and .8x reducer as that setup will have a shallower depth of focus.

During this year's eclipse Venus should make a good focusing target as it will be just over 40°W of the Sun. Sometimes aircraft or their contrails can also be used as a daytime focusing target.

---John

Well I guess it's official--- Mars season is back underway! This is the first image I've seen this year with easily recognizable features--- not easy when Mars is still under 5". Fine work, Dan!

BTW--- how wide is the bandpass of your H-a filter?

---John

Thanks for the comments Stefan and Kevin!

Unfortunately not many try to image Mercury so there's simply not a whole lot of images out there. Here's what's possible given an unusually good run of clear and relatively stable skies from mid October to early November of last year:

http://home.comcast.net/~jeboud/mercury_oct15_to_nov2.gif

---John

Very fine image Paul!

I hope some of that great seeing makes it's way to New England soon.

---John

Nice shot Steve!

I was out at the same time, seeing only fair at best but with thin intermittent clouds up here in eastern MA. A couple of camera glitches too but I think I've got some good AVI to work with. Might get to them processing tomorrow.

---John

Fine shot Steve!

I see that you're using 60fps. A few weeks ago on CN there was a thread with convincing proof that the Imaging Source cameras have an artifact problem at 60fps, basically a 'ringing artifact' similar to the ones we see many times on a sharp-edged sunward limb, but located quite a bit further inward than the typical limb ringing.It appears that you may have this in your image.
http://tinyurl.com/y9sxy2o

The OP has a link to the same topic on the Imaging Source Forum:
http://www.theimagingsourceforums.com/showthread.php?t=322823

Here's a Jupiter animation by Emil Kraaikamp with the problem:
http://www.astrokraai.nl/dump/ANIMATIE_smoothklein.gif

I've been using 60fps for Mercury, but the limb of that planet apparently isn't bright enough or well defined enough for the problem to show up in typical daylight seeing. I have had some problems with Venus at 60fps though. I now plan on 30fps as the maximum for these cameras.

---John