Posts Made By: Wei-Hao Wang

Hi,

It's normal. When my (NJP) reticle is verticle, its RA is off center too. The only thing important here is, the reticle has to be verticle.

Cheers,
Wei-Hao

Emanuel, I suggest you look for a modified Nikon D50 or Canon 350D. They should be quite cheap now but still perform well. For more information, I suggest you look at the digital_astro Yahoo group. There are quite a few DSLR experts on that group. Personally I don't know much about the newest DSLR models. You may also want to look at Jerry Lodriguss' website. His new book on DSLR astrophoto is very good.

Cheers,
Wei-Hao

Hi,

For 5-10 min of exposures with <400mm lenses, nothing is better than TAK P2Z. It is very portable, stable, and tracks accurately. 8-12 lb is the right range for P2Z too. Its polar scope will allow a polar alignment much better than Sky Patrol, and at least as good as Vixen GP or SP, if not better. TAK Sky Patrol is great, but is perhaps only for lenses shorter than 180mm. If you want a goto function, then perhaps Vixen Sphinx is the way to go.

Hi,

This is a nice picture.

At the begining, I looked at the title and thought "hmmmm, Tak 180ED.... a new Tak APO refractor that's even larger than TOA160?"

Then I realized this must be Epsilon 180ED.... I'm stupid.

Wei-Hao

Hi Ivan,

Do you mean a 48mm filter? Based on my experience on E160, the TAK wide-mount for SLR/DSLR accepts 48mm filters.

Wei-Hao

Hi,

Did you use drift alignment?

Wei-Hao

Couple of months ago, TAK was advertising (in Japanese magazines) upgrade corrector lenses for Epsilon250 which turns old E250 into E250ED. If someone wants an E205ED, buy E250 and get a new corrector lens from TAK.

Wei-Hao

Hi,

How about using a distant daytime object to test how much more distance is needed to reach focus? In this way, you will know if a CAA is enough.

Hi Daniel,

The official number of Sky90's image circle (when used with the reducer/flattener) is 45mm diameter. This is not enough to fully cover a 645 frame. My guess is that you will get a circular illuminated area of slightly larger than 50mm. Personally I like such kind of pictures, but I do know that some people don't like this.

It is not too easy to get a Ronchi or knife-edge focuser for Mamiya 645, I guess. I usually focus my Mamiya 645 with Takahashi FM60 microscope. The result is always perfect but it is not easy to operate. (It is especially difficult on Mamiya 645.) If your camera is the newer Mamiya 645 with removable finder, an easy way to focus is to use a high magnification loupe (at least 10x, more than 20x is preferred), and directly focus on the focusing screen of Mamiya 645. Sometimes I do this, and I don't remember I ever got a bad focus.

I saw some pictures taken with E100GX, they are decent. However, to get the most red nebulosity, E200 is a better film to use. It is faster too.

The biggest problem I see in your setup is tracking. To get decent images with Sky90, just a few minutes of exposure is definitely not enough. You will need to go for at least 15 or 20 minutes. P2z is a great mount, the best one can dream of in its class. However, I don't think it can guarantee pinpoint stars with the focal length of your telescope and with exposures of 10+ minutes. On the other hand, Sky90+Mamiya645 and a guide scope are probably pushing the limit too much on P2z. It may work, if you can find a light-weight guide scope.

My suggestion is, go out and shoot anyway with whatever you have now. Try E200 (one or two stops of push processing) and expose for anywhere between 10 and 20 minutes, and see what the result is. Then you can consider how to improve your setup based on the result.

For your reference, this is a homepage of a Sky90 user:
http://paulimer.sinastarz.com/
He uses Mamiya 645, Sky90 with reducer, a guide scope, and a small mount (Mizar New AR) that is not quite as good as P2z. He managed to get many excellent photos. I am not sure if the images were taken with Mamiya 645. Even if yes, the images on the website must have been cropped. He was facing the same problem -- the telescope and the guide scope are too heavy for the mount. Later he moved to TAK EM11 but most (if not all) of the images on the website were taken with the small mount. As long as you can focus well and track well (for 30+ minutes), you can expect to get similar photos.

Hope these help.

Cheers,
Wei-Hao

Hi,

That's definitely possible. My PD5XY controller was modified to allow autoguiding. Unfortunately, a friend of mine did that for me. I don't know how to do this.

10 years ago, modifying the controllers for autoguiding was a very common practice for Japanese EQ mount users.

Good Luck.
Wei-Hao