Posts Made By: Al Arduengo

I am rather new to AP and am having some issues I need help with. I do not own a wedge but rather a field de-rotator that came with the LX200 10" I purchased. I have read some articles on this where most folks seem to stay away from de-rotators and opt for wedges. Being the rebel I am, I would like to try and get some use out of this thing and avoid spending more $$ on a wedge. My goal is not to produce photos that look like the stuff in the magazones, but more to produce shots that look similar to what the user would see in the scope.

My questions are:

1. Is anyone doing film AP using the de-rotator?
2. If so, can you offer some advice and experiences to a newbie?
3. My first attempt at using it resulted in what I first thought to be rotation and led me to believe the device was not doing what it was supposed to. After more examination, I have come to believe it may be due more to drive error in the scope itself. Just how long can I expect to be able to expose using a de-rotator without having to worry about inaccuracies?
4. What is the simplest, cheapest AND most effective way to guide when this beast is attached to the OTA?
5. Are there any examples of work done using the de-rotator I could see to motivate me?

Thanks for any assistance.
Regards, -Al A.

Hi all,

I haven't gotten a response to my post "Any success with field de-rotators?" but I imagine the general feeling is they are no good. Still, I am determined to get some use out of it. As I said before, I am not interested in exposures longer than 1-5 minutes. With this in mind, I also do not need auto guider capability (wouldn't be able to get the wife to ok the expense anyway) but I know I need *some* guiding. I have never done it so are there suggestions for the best way to do it? I suspect my choices are off-axis or guidescope. The off-axis guider seems like it would be the least cost prohibitive except that I would have to also get a reticle eyepiece. Would it need to be illumintated or are non illuminated ones useable? Is an off-axis guider even meant for use this way? If not, what would be a good suggestion for a guide scope?

Thanks,
-Al A.

I have been dabbling in film astrophotography for a small time and trying to find the right combination of film, skies, exp times, etc. My last attempt was at Saturn. My intent was not to create great images but more to find out how my combination of ep and sky conditions were affected by exposure time. I was shooting afocal with Saturn about 20 degrees up. My skies are about mag 4 but I would expect to be able to do something like planetary. I took the whole 24 exposures in groups of four shots, each group used a progessively longer exposure time with the first set at 1/125. I was using Fujifilm 200 (the 4th extra layer stuff, whataver that actually does I have yet to see). Now, I have had limited success taking my film to both the local 1-hr as well as a pro shop. Since this was experimental only, I went with the 1-hr lab. The results were an entire roll (*except* for the first frame which I always make of a bright daytime object) of completely white frames. Almost as if everything in the dark was over exposed but not even a little detail I could see. In the past I have had rolls turn out similar to this except all light blue (again except for the first well lit shot).

My questions:

1. Is this a recognizable problem to any of the veterans?
2. Why would all dark sky shots be white?
3. As I understand it, the actual development of the film does not introduce any color corrections so whatever is on the film should get developed. Is this true or is the 1-hr lab actually screwing up my film?
4. I suppose there is no way to salvage film that consists of a roll of white frames? (rhetorical question I guess)
5. What brand/speed of film is best for moderate levels of light pollution for use on brighter DSOs and planets?

I am using both a Pentax K-1000 and a Minolta SRT-102. Both camera work perfectly for normal photos so I am ruling out faulty equipment. Also, I use a de-rotator for everything except planets/moon/solar and a wedge is out of the question right now (ask my wife, she will tell you) so please don't suggest getting a wedge. I know, I know... :-/

If I could just get two rolls in a row to come out useable I would have something of a system and I could enjoy this more.

And if it matters, I have a LX200 10" Classic and I use either a 12.4mm or 26mm ep for afocal shots at f10 (no focal reducer....yet).

Thanks very much for helping.
-Al Arduengo