You say you are concerned about brightness dropping off as you go up in power. That it going to happen with any scope of any aperture.
Hi all - I'm looking to upgrade my Explore Scientific AR102 to something with similar aperture and focal length. I want to try to get the best grab-and-go scope that I can within my price range. Don't get me wrong, the AR102 is a fantastic rich-field telescope and I've totally been enjoying it. While it's truly great at low power, I feel like the brightness/clarity really falls off when I start going higher than about 50X on most DSOs. Given that the scope yields generous exit pupils with most eyepieces, I figure it must be that's what you get with standard crown and flint optics. There's also some CA in the AR102, but that's not that big of an issue for me. If I can get rid of it, then cool, but it's not my primary motivation here.
So I'm looking for a higher-end scope to compliment or possibly replace the AR102. Really high end is off the table, so no Takahashi or Televue for me unfortunately. Happy to entertain ideas up to around $1000 or so. I'm also leaning more toward doublets than triplets. I'm a purely visual observer so no need for AP-ready scopes here.
My current research has resulted in these two Astro-Tech scopes:
- AT102ED 4" f/7 - $600
- AT102EDL 4" f/7 - $1100
The stats on these two are pretty close to what I'm looking for. But the EDL version costs about twice as much as the basic ED version. What gives? What would I be paying for if I went with the EDL? Can those who know about these things comment on the difference between the optics in these two scopes? Is the upgrade to the EDL only something to consider if I want to do AP?
Thanks in advance. If it helps, here's a list of eyepieces that I usually use with this scope.
- ES 24mm 68*
- Meade 18mm 60*
- Orion Stratus 13mm 68*
- Agena Astro 5mm "double ED"
Bortle 4/5 skies at about 1400' elevation.
As you go up in mag you are viewing less and less of the captured light cone, spreading it out to create the higher mag image. Brightness is going to drop off. No way around it.
To get brighter images you need more aperture. Maybe you should be looking at the AR 127 if CA is not a concern. 55% more light capture.
When you figure prices, make sure you know what is NOT included.
I just ordered an AT102ED. I have several friends who have them and they LOVE them for visual. Makes a great companion to a large Dob or SCT.
Note that the AT102ED does not include a diagonal. So add $75 to $150 for a diagonal.
No finder scope so take that into account in your budget.
It does have rings and dovetail.
If you keep the Explore Scientific AR102 you could share the diagonal and the finder with the AT102ED. Otherwise plan to buy these
Both the ES and AT have dual speed focusers. The AR is F6.5 vs that AT at F7, so not a big change.
CA Reduction - I am no optics expert, but based on what I have read, you can expect about a 90% reduction in CA in the 102 ED as compared to the standard doublet, but not true APO triplet results. But for visual, the reports are just excellent.
The question is, what would you hope to gain for double the money, going to the EDL? Getting rid of another 6% of the CA? This is still a doublet so still not a full triplet APO.
I am upgrading from an 80 mm F5 doublet achromat. I voted with my money on the AT102ED. You may have higher expectations than I do.
Astronomics can't keep the 102 ED in stock. Not going to be available till the end of October. Don't know how many people already have claim to the next shipment or if I will get one. I can wait.So, what is your goal for upgrading, since you say the CA doesn't really bother you? Going to ED is about CA reduction, not a brighter image, as I understand it. You may be buying for the wrong reason.
Edited by aeajr, 13 September 2020 - 03:37 PM.