Posts Made By: James Sarte

Who makes these, and approximately how much do they cost? I've looked around, and have not found much information regarding these solar filters.

I decided to purchase a new digital camera last night, an Olympus C-5050Z. I decided to test it out with my Konus reflector which I just set up outside, and did not give sufficient time to cool down. I am curious what is the proper procedure for taking pictures in this method? In my case, I just held it up to an eyepiecec which gave me the full FOV through the LCD in the camera. I took a few shots of the moon and this is what I got:

Hello everyone. I have a pre-2004 1st generation Konus 1793. I also own a Canon 20D and a 300D. I just have a few simple questions regarding the mounting and usage of my digital cameras on my telescope.

1. How do I attach the camera to my focuser? I realize that there are T-mounts made for SLR cameras, but is that all I would need?
2. Regarding question 1, if I purchase just a T-mount, my scope basically becomes a 2000mm f/5 lens. How do I increase the focal length? Is there some kind of barlow that is designed to mate with a t-mount? Am I also correct that if there is some kind of barlow (2x perhaps), that my scope then becomes a 4000mm f/10 lens?

Thanks.

James

P.S. I should perhaps state my reasons for wanting to hook up my SLR's. I'm still learning alot about astronomy, so serious astrophotography is probably out of my league. What I do want to accomplish is to take nice pictures of the moon or other planets without having to hold up my camera and lens to the EP, as I have done previously. The attached photograph of the moon was taken with a 25mm plossl and at the time, an Olympus C5050 help up to the EP. Now that I've upgraded to digital SLR's, I was hoping to get the most quality out of my lunar shots possible.

Hello everybody. I have had my 1st generation (pre-2004) Konus 1793 8" reflector for over 2 years now, and am quite embarassed to say that I've never bothered to learn how to use my setting circles. I am now in the process of attempting to use them to locate objects for the first time, and was hoping that someone with a similar scope or mount could help me.

1. The RA setting circle has two moving rings. The first main ring with the numbers 1-24 has a thumb screw that locks it in place. When you adjust the RA axis, if this thumbscrew is tightened down, this ring doesn't spin.

2. The second RA ring that's inside the main ring does spin however, and can be moved by hand.

Can someone explain to me why there is a lock thumbscew that holds the 1st ring? Any other info that anyone can give me for this particular mount would be great.

Thanks,

James

I've been having some trouble lately getting a good telescope. The last few units I received (vendor's name withheld) have all had problems. Example, one Maksutov I received had grease on the secondary, the replacement Mak had a loose rear mirror cell that wouldn't tighten down, and collimation was way off.

Now, I received an achromatic refractor which had some sort of residue all over the primary. Instead of sending it back again, I decided to just clean it myself. I suppose due to my frustration, I didn't take the time to clean it carefully, and as such managed to put a few very light scratches in the coating. Of course, these scratches are only noticeable when shining a flash light down the tube.

However, since this being my first refractor (I've owned plenty of newts, and know how to care for my optics), I'm a little concerned that image degredation might occur.

I reassembled the doublet, and recollimated and so far star tests seem okay. Advice? Suggestions? Should I worry about it, or just let it go... the telescope is a fast 80mm f/5, so I'm doing mostly widefield viewing with it. No photography.

Thanks!

OK... I'm starting to second-guess myself on my collimation results with an ST80. Hopefully, someone here can give me some insight.

Firstly, diffraction patterns are good. Nice, airy disk, symmetrical rings, etc. However, racking from focus to inside focus then outside focus sometimes shows the original focus point to be slightly off-center.

It's hard to describe without a visual aid, but imagine a star that's perfectly in focus. When you rack out of focus, you expect the center of the diffraction ring to originate from the center of the star, with the diffraction rings growing concentrically outward. What I sometimes observe is the center of the diffraction ring originates not from where the star's center should be, but off to the side. The inside of the airy disc is clean, and uniform. And the two out most concentric rings are clearly delineated.

Still, I get nice airy disk with no signs of visible coma or astigmatism.

Suggestions?

Thanks,
James

Picked up a new 120mm refractor tonight, and gave it a quick test and one over. Collimation seems good right out of the box, but the tube itself looks like it took a bit of a beating during shipping to the retailer. There are no dents, but the styrofoam ends holding the tube in the box was disintegrated. The focuser was also a bit skewed, and the paint around the focuser screws that secure the focuser to the tube was a bit chipped off. I was able to restraighten the focuser in its tube, and collimation improved. On a more serious note, there appears to be something like tiny metal flakes or specks sandwhiched between the doublet pair. It could be dust. I'm thinking metal specks because they look shiny when focusing a flash light on them. There's also a very light .75 - 1" coating scratch on the secondary doublet inside the tube. Can't really see it unless looking at an angle. The lens facing outward is clear, and coating is uniform.

Question is, should I exchange the tube? I was fortunate enough to pick this up from B&H which is near my apartment, and as some of you may know have a very generous return/exchange policy.

If anyone has dealt with B&H before regarding telescopes, would they let you swap tubes if the package included a mount? The mount I received is a modified CG-4, and is in good shape except for the RA setting circles which are loose and appear very flimsy.

Thanks,
James

P.S. Anyone know how to take the focus knobs off? This one does not have a center retaining screw, and I can't see any allen screws attaching the knob to the post. I'd like to install my electric focuser.

Wondering what max usable weight capacity is on the current CG-4 (Celestron) / EQ-3 type mounts with sealed ball bearings in both axis, and upgraded 1.75" tubular steel legs?

Just wondering what you guys think; decided to connect my old 20D to the back of a Celestron Omni XLT 102 refractor using prime focus. Mount is a CG-4. Unguided obviously, eyeballed north as I can't see Polaris from my balcony, plus a full moon was out. This was shot at 800iso for 20 seconds. Cleaned it up a bit in Photoshop afterwards. Now the image isn't as good as I'd like, but I think the imaging bug has bitten!

I guess the "hand figured" optics claim by Celestron isn't a joke!

Star tested my 102 tonight on Sirius.

OTA was initially out of collimation, but a few tweaks on the mirror cell corrected that.

Waited about an hour for the tube to acclimate to the surrounding temperature, then did several inside and outside focus tests. Unfortunately, I have no way of recording what I saw visually, but will do my best to describe what I saw. Diagonal was a 1.25" Orion dielectric, EP was a "generic" 6mm plossl. A Baader fringe killer was used as well. Mount is an LXD75.

Inside focus: nice, concentric, well-defined discs
Outside focus: also very nice, well-defined discs

No obvious spherical aberration or over/undercorrection. No sign of astigmatism, or turned down edge. In fact, inside and outside star test patterns are essentially identical. If I could make an estimated guess, optics show at least 1/7 (maybe even 1/8) wavefront pte.

Confirming my visual test with images on Mark Ludes' website, the following pictures are the closest in representing what I see through the EP.


http://aberrator.astronomy.net/scopetest/html/refractor100_8.html


http://aberrator.astronomy.net/scopetest/html/refractor_100_5.html

Suffice it to say, I am VERY pleased with the optics in this refractor; with star test results(and I'm bound to irk some here with this) rivaling those refractors of much higher cost. Of course, there are some caveats; this is the second Omni OTA I've gotten from Celestron. The first was a 120mm with metal flakes between the doublet pair, and uneven coating. As I said before as well, collimation was way off out of the box. The fact that this is an achro also shows CA on bright objects, but a reasonable trade off considering the price paid for the OTA and mount together. All in all, I would highly recommend the Omni XLT refractors.

Regards,
James Sarte