barlow question

Harpspitfire · #1 25-08-2011, 09:10 AM

i want to image jupiter later on, but only have a 2X antares barlow for my 9.25, i used to have a klee 2.8X but sky conditions NEVER let have a good focus, i dont wanna buy a 2.5X powermate for all ill use it for, anyone have experience with the new 2.5X cheap line out? i think they're all from the same place branded like- OPT, Relevation, Smart Astronomy and GSO- tia, john

asimov (John) · #2 25-08-2011, 11:51 AM

I'm using an old Meade 2X & I add an extension tube to get very close to 3X. I'll assume you could do this with your Antares as well.

Harpspitfire · #3 26-08-2011, 01:39 AM

i do have an extension tube (old gutted out barlow)- but i thought they had to be spaced properly for proper focus?

Merlin66 (Ken) · #4 26-08-2011, 08:57 AM

No.
With the traditional Barlow if you increase the distance between the lens and the eyepiece/ CCD the magnification increases.
You should be able to re-focus as normal.
BTW I found the Klee x2.8 to work very well for me on various scopes....

asimov (John) · #5 26-08-2011, 04:08 PM

As Merlin said. The only barlow/powermate that doesn't work this way is the TV 2.5X Powermate. I think my extension is just over 115mm long, which gives me just shy of 3X with the 2X. You will still be able to come to focus as the SCT has plenty of room in that area. Just dropping another (without the elements) barlow in on top may give you too much however. You'll have to experiment in that area.

The Klee 2.8X should be perfect in good seeing actually, with a well collimated scope. I also recommend not skimping on barlows/powermates. I've used a few el-cheapo barlows, but I wasn't stupid enough to purchase them thankfully. Save up & shop wisely.

Harpspitfire · #6 29-08-2011, 05:23 AM

ok, ill try out my extension on jup when its gets a little better placed before i get another barlow- i just found out my antares may not be the 3 element APO as it was supposed to be!- its older, but i see antares has 3 1.25 sizes- the cheap one and 2 with red lettering as mine has- my also says made in japan but has no other numbers on it- i rememeber the dealer telling me when i bought it, it was same as the celestron ultima, but i cant seem to verify that now