Beginner Help

[Bat502]

I`m interested in doing some Astro Photography. At present I have a Skyliner 250PX Dobsonian (Solid Tube & Manual operation). Do I really need to get a Synscan to get the best quality photos. Also what camera would be suitable for this type of scope. I am told it is a "fast" scope. What does this mean in terms of photography. No doubt there will be more questions, because at present with the NEQ6 mount, Mounting rings, Camera and power tank, this is going to turn out quite expensive. Could I not get a decent camera, attached to eyepiece and take lots of short exposure pictures and stack them?

Many thanks.

[VigdisVZ]

Hi

The synscan is just the handset, you could easily get the syntrek version of either the HEQ-5 or NEQ-6. I'm not sure if the focuser has enough move to allow focus with a camera attached on the 250PX so hopefully someone could fill us in on that.

While the NEQ-6 could handle the 250PX, it would be very bulky to work with, it might be wiser to keep the dobson as it is and build up an AP rig on the side. Besides, the dobson will be your best friend to keep you company while the AP equipment is minding its own business.

While the dobson is fast the focal length is 1200mm which means that the field of view is narrow compared to say a 150PDS or a 80ED (both popular beginners AP scopes).

The best camera would probably be a non modded DSLR as it can double as a normal camera during daytime. Or... which leads me to your last question, taking short exposures, thats basicly what you do when you shoot planetary like Jupiter and the Moon with a webcam. Technically you dont need a mount for that but could pull it off if you're quick with moving your dobson. However short exposure photography with a larger sensor DSLR is basicly only viable when going for the moon.

Fast means (in my non expert head) that the ratio between the focal length and the aperture is low. Roughly it collects more light from a wider area of the sky. It doesnt mean that it collects "more" light than say a 250mm SCT, it just has a wider field of view. You should read up on F-ratios if you're interested. http://en.wikipedia.org/wiki/F-number

There is a myriad of ways to about when starting out, the most important thing is not to put any money down before you've researched the path you're going to take.

Hope this helps a bit.

[Bat502]

Interesting post. Since I wrote this i have been looking at posted images. the posters are saying that the images they took are guided and unguided. What do they mean? Am I assuming correctly that they are using a synscan (guided) manual (unguided)?

[VigdisVZ]

No, a synscan is just a small portable goto-computer. Guiding is when you use a separate camera and a small scope on top of your regular imaging telescope to lock onto a star. This allows a computer (either a PC or a small stand alone device) to send small corrections to the mount as it tracks the sky. This allows you to go from 1-2 minute exposures to basicly limitless (thought the norm seems to be around 5-10 minutes depending on your equipement).

[VigdisVZ]

Honestly, if you're interested in this, the wiset thing to do is grab a copy of Steve Richards book "Making Every Photon Count". It's an excellent guidebook to break into deep space photography and will probably save you money, time and frustration in the end.

http://www.firstlightoptics.com/books/making-every-photon-count-steve-richards.html

[swag72]

Before you fork out any more ££'s can I suggest that you buy the book 'Making Every Photon Count' from the FLO website in the book section. It really is the definitive bible for those starting out in AP, well written and well regarded.

The most important part of the AP setup is the mount and this can not be stressed enough. Looks like you've already got an NEQ6, which is an excellent start. From there an often made recommendation is a short focal length refractor scope, such as an 80ED. A good starter scope, that is the most plug and play you can get.

AP is all about long exposures. I regularly take 30 minute exposures. For that you need a way to guide your mount. An NEQ6 will track for a short while if Polar aligned well and you may get a couple of minutes exposures without star trails showing. But this is where the short focal length scopes come into it, they are so much less taxing on a mount. So you can guide in 3 ways really. I use a finder guider scope with a separate camera and hooked up to a PC. You can use a standalone guider, or another way is an Off Axis Guider (OAG). It's all in the book and also probably a bundle of threads explaining it. I don't want to be responsible for making your head explode!!!

[Bat502]

Yes I will get that book. Many thanks for your responses.