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Posts Made By: Stanley Feather

August 14, 2004 01:22 AM Forum: Refractors

Vixen ED130SS, NA130SS, NA140SS?

Posted By Stanley Feather
I use the NA120SS for DSO photography, and I love it. Compared to my SCT it has far better contrast, flatter field, and the stars are pinpoints. I'm always amazed at how detailed and sharp the slides can be, about as good as from the Nikon lenses I use for widefield. I've taken lots of bad photos, but I've definitely learned it's not this scope's fault.

I wish the focuser was in the same class as the optics, but it's really not that bad. I've thought about upgrading to a Tak or AP focuser, but haven't worked through what that means yet.

There was an NA130 for sale at the same time I got the 120, but I didn't know anything about them and decided to go low, just in case it didn't work out. Now I regret that just a little, but the 120 has been a great scope for me.

sf

August 21, 2004 04:03 AM Forum: Equipment Talk

Nikon FG

Posted By Stanley Feather
A locking mirror is actually better for lunar and planetary photos, it's not necessary for deep sky.

On deep sky, the exposures are long enough you can use the 'hat trick' during release and before closing.

On planets and the moon, the exposures are way too short for that, so a locking mirror is 'a good thing'. If your mount is really steady it might not matter much.

My Nikon FE2 doesn't have a mirror lock, but it does have a cool feature that works just as well. If you set the delay timer and hit the shutter release, the mirror swings up immediately. Then after the delay (about 5s-10s) the shutter opens, then closes, and the mirror swings back. The 5-10s is plenty of time for vibration from the mirror to settle out.

I don't know if the FG does that, but it's worth looking into.




September 4, 2004 04:17 PM Forum: Equipment Talk

Directions and Drift Alignment

Posted By Stanley Feather
Vittal,

Here's the method I use.

http://www.aa6g.org/Astronomy/Articles/drift_align.html

Based on that method, the answer to your question is: you only adjust the mount to correct north-south (DEC) changes. If you see east-west changes you can either ignore them, or correct them.

I guess if you have *significant* east-west motion, something is wrong. I haven't seen that problem. (I did swap the RA and DEC motor cables once. That was interesting)

As has been mentioned, you should polar align before engaging PEC.

sf



September 12, 2004 04:10 PM Forum: Equipment Talk

Lumicon products verses other options

Posted By Stanley Feather
Hi David,

I've had the newt guider for a few years, and it was worth the price difference. It's a superior design, and mine is well made, and no plastic anywhere.

I don't know if their eyepiece / illuminators are worth a premium. I'm using other brands for that stuff.

sf

October 24, 2004 08:27 PM Forum: Equipment Talk

SCT Dewing

Posted By Stanley Feather
Not inside, just on the outside of the corrector.


November 2, 2004 04:42 AM Forum: Equipment Talk

Off-axis Guider Recommendations needed please

Posted By Stanley Feather
I'm using the 2" Lumicon on a refractor. If (or when) I decide to do photography with my SCT I'll get the Lumicon SCT version, too. They're really well made and have some nice features. They cost more than some other brands, though.

On the SN check the guider dimensions against the available in-focus travel. Most newts don't really work with OAGs, for this reason.

Consider the 2" or SCT-threaded models (assuming your scopes have that capability) to minimize vignetting.

sf

November 5, 2004 04:17 AM Forum: Film Astrophotography - Imaging and Processing

first time sky portraits

Posted By Stanley Feather
Reeves' book gives the following unguided exposure times for trail-free images. These assume you're 30 to 60 degrees declination. They're shorter if you're closer to the equator, longer if you're closer to the pole.

28mm lens: 50s
35mm lens: 40s
50mm lens: 25s
85mm lens: 15s
135mm lens: 9s

Most lenses will show some spherical aberration at the edge when wide open, so consider stopping the lens down 1 or 2 stops.

Good luck.

sf

December 11, 2004 05:55 PM Forum: Equipment Talk

Heat on SCT's: how much is just enough?

Posted By Stanley Feather
Hi Ivan,

All the DewBuster and the new Kendrick controllers do is keep the temperature a few degrees warmer than ambient.

Maybe you could get one of the cheap indoor/outdoor digital thermometers, put one sensor under the strip, and one in free air. Every half-hour or so you could check the difference and adjust the controller.

It's a bit of a pain, but at least you're not guessing.

sf

February 6, 2005 04:57 AM Forum: Equipment Talk

Philips ToUCam 740/840 webcam mods

Posted By Stanley Feather
Search for 'sc1 modification'.

I haven't gone down this route, yet. But it's starting to look pretty attractive.

sf

April 8, 2005 02:21 AM Forum: Equipment Talk

Radial (off axis) guiding for my Digital imaging?

Posted By Stanley Feather
For long exposures you need some type of guiding, whether you use CCD or film. Usually that's with an off-axis guider, or a guidescope.

I'm a bit surprised DSLR Focus works well for guiding. I don't use that sw, but I did peek at their website and they didn't mention guiding as a feature.

In particular, I'd expect any errors shown by the sw to show up on the image. It's too late at that point. The guiders allow you to detect and compensate early enough to keep the image sharp.

But, every application is different. If the sw works for you, the guider is certainly redundant.



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