First telescope with the ASI2600MC Pro

You cannot go wrong with any of these. I can't tell you which is the absolute best, though. Sorry!

[pre]I use the ASI 2600 MC Pro or 2600 MM Pro and the SW esprit 100.
The whole thing is perfect[/pre]

Hi!
The Esprit 100mm is an excellent choice, considering that it is a proven and reliable option in terms of quality. You can be confident that you won't be disappointed.
As for the SQA-85, there isn't any quality data available yet.
However, the spot diagrams provided by Askar are simply impressive – I haven't seen such spots in any other telescope, including Takahashi.
If the actual spot quality is close to the spot diagram, it will be an absolute favorite in this budget.

I am very happy with my Askar FRA 400, and wil recommend this as a versatile and handy telescope!

Hi,
​​​​​​I have a TS Imaging star 4,4. I use a NBZ 2" filter. Backfocus was at first a problem. I will post my latest images on astrobin soon. I made some mosaics that I like with these instruments.

Michael:
Hi!
I am relatively new in the DSO astrophotography and I could use some help in determining what telescope I should get. 
I have.
ASI2600MC Pro
AM5N

  I was hoping to keep the cost below $2500  but if there is a clear winner like the Esprit 100, I will save up for that.   Ideally I would want the telescope to be no slower than native  f5.6 (without a reducer) and looking at focal length 400-500. My choices so far are:

FRA400/FRA500
Esprit 100mm ED Triplet APO
Askar SQA85 Quintuplet Refractor

I would love to hear from the community on which one out of the four above they consider the best and or what other options I have missed.

Thanks again in advance!

Michael

I just went over to CN and found this posted over there. Not sure where your located but gives you an idea about second had pricing.

https://www.cloudynights.com/classifieds/item/388099-askar-fra500-with-f39-reducer/

Dale

FRA400/FRA500
Esprit 100mm ED Triplet APO
Askar SQA85 Quintuplet Refractor

I would love to hear from the community on which one out of the four above they consider the best and or what other options I have missed.

Michael, 

I think any of them would be fine choices.  There are some other scopes in the Askar brand that would be good choices too.  Additionally, some of the William Optics scopes would be good choices.  The ASI2600 sensor at 2.76u works well with a wide range of focal lengths.

I think a good place to start is with the image scale and determining where a given scope/focal length falls in relation to  being under, ideal, over sampled.  Use the tool in Astronomy Tools, https://astronomy.tools/calculators/ccd_suitability.When I use the tool, I usually keep it set for OK seeing as in my area (Vermont) the the nights of Good seeing are few and Exceptional seeing is rare.  The tool is not a hard and fast rule either, but it is a good guide to let you know if you are far over or under samples.  According to the tool, anything from 400-1100mm focal length is ideal sampling, but even though 300mm might be considered undersampled, you would probably not notice it once you collected and stacked a few hours of data.  The same is true for longer focal lengths such as a C8 SCT at 2000mm or with a reducer at 1280mm. 

John Schnupp, N3CNL
2007 R1200RT +79,300
1995 XLH 1200 106,495 (retired)
Georgia, VT44.7675°N, 73.1592

I'd encourage you to go with a scope that has a reducer associated (e.g: FRA or FF) this gives you a lot of flexibility!

Michael:
FRA400/FRA500
Esprit 100mm ED Triplet APO
Askar SQA85 Quintuplet Refractor

Hi I once had FRA400, and now I have several scopes around 300-500mm (65PHQ, FRA300, SQA55, 80PHQ, VSD90SS)
I can recommend these two. FRA400 was sold when I got 80PHQ.

80PHQ + Reducer, 455mm f/5.4, $1,548 = very sharp on center, budget friendly
SQA85, 408mm f/4.8 $2,395 = not field proven but we can expect incredible sharpness. 

these are bit expensive
Esprit 100, 550mm f/5.5, $3,210.
Vixen VSD90SS, 495mm f/5.5, about $4,500. 

400mm-500mm + APS-C is very nice FOV, you can enjoy famous nebulas.

FYI I believe the FRA 500 has the best perf of the FRA range, certainly there are a lot of concerns about the 600 … esp relative to the 500 … also aperture is king!

Our local astronomy club has the SW Esprit 100 setup in the observatory.  Its one year old and the screws on the bottom of the focuser are already rusty and the dew shield is sloppy.  Photos with our 2600MM Pro are ok.
I own an Askar FRA500 and its a really nice Petzval.  I went with it as I was in the same boat as yourself.  Our clubs Esprit turned me off it.  The dew cap is decent and does not move…  The focuser is nice and sturdy.  Overall I reckon built way better than the SW.  Photos are fine with a 2600MM Pro.  I do have the Askar reducer (my boys bought it for me as a gift) sort of defeats the purpose of a petzval design but nice photos.  Using ZWO spacers its not at 350 focal length but 348mm.

I got the Esprit 100mm, its perfect and durable.
I would suggest it if you not using in travel (most the time).. its a little bit heavy..
And I think those who own the AM5 love a light weight setup
The second choice would be the Askar SQA85, Now I don't own this model, but I have the ASKAR ACL200 and its great optical so, its a comparison idea.
Clear Sky !!