Will this be a suitable guidescope?

cloud_cover · Post by **cloud_cover** » Sat Aug 14, 2010 12:21 am

Gary is selling a Meade 2090 90mm f8.8 achromat, 800mm focal length.
Do you guys think this will make a decent future guidescope if and when I do finally purchase a main scope? Considering cos' price is nice

Also intend to use it visually for now, of course

orly_andico · Post by **orly_andico** » Sat Aug 14, 2010 12:26 am

Too long.

Guider chips are really really tiny (Toucam equivalent to a 5mm eyepiece) so it will be really hard to get a bright star in the field of view with a tube that long. But that telescope will serve as a good visual instrument for the moon and planets... with an EQ mount of course.

cloud_cover · Post by **cloud_cover** » Sat Aug 14, 2010 12:36 am

I see. So for a good guidescope I should instead consider a shorter tube with a shorter focal length?

orly_andico · Post by **orly_andico** » Sat Aug 14, 2010 12:38 am

According to Stuart (croys) you can guide effectively with a 50mm lens. I have read much the same online. One of these days I'll get around to making my 1.25" to M42 converter...

Gary · Post by **Gary** » Sat Aug 14, 2010 1:19 am

I have no idea what scope is good for guiding on what main scope. But just for kicks, here are some pics I image googled:

cloud_cover · Post by **cloud_cover** » Sat Aug 14, 2010 3:29 am

Thanks for the googling!

KKK26 · Post by **KKK26** » Sat Aug 14, 2010 8:46 am

The refractor in the last pic is so impressive. What brand is it?

For consideration, you will need bigger dry cabinet to keep refractor. I still saving $$ to buy 160L cabinet to keep my scope. Bcos they sell COD only.

MooEy · Post by **MooEy** » Sat Aug 14, 2010 8:58 am

that's a tmb 105/6.2?

timatworksg · Post by **timatworksg** » Sat Aug 14, 2010 5:31 pm

Or do what I did and break apart a 50mm Bino and DIY.

http://www.singastro.org/viewtopic.php?t=8363

Saved me lots of money (spent no more than $40 max), plop in a Meade DSI and fire up PHD. Besides you don't need super sharp stars to guide. As long as you have a fuzzy one and it moves well enough for PHD to calculate...you get 'green' crosshairs everytime! And after my last Hack to my DIY guidescope, 2" extension tube collars fit very well into 50mm PVC pipes. This makes connecting adaptors, focusers, etc very easilly! Plus the whole thing adds the right amount of weight fore of the scope to balance out the DSLR on the bottom end.