POLL: Would you rather shoot with a Quattro 8 inch f4 with 585mc pro or Edge 8 hd at f 10 with 2600mm pro at bin 2?

Jim Waters:
I owned the Quattro 8 f/4 scope and ended up selling it at a significant loss.  There are numerous issues that need to be addressed to use it as an imaging scope.  The Crayford focuser is inferior, slips and requires rework.  Its best to replace the focuser with a good quality R&P focuser.  The mirror cell can pinch the mirror and needs adjusting.  There's no aperture  mask to hide the mirror clips.  The secondary spider is very problematic and its best to replace it.  There are many light reflection and light leaks throughout the scope.  The scope tube needs another 6 to 8" of length from the spider to reduce stray light from hitting the mirror at odd angles and entering the focuser draw-tube.   ...etc.

It was a bad investment.  YMMV

CS
Jim

Hi,

Honestly speaking, all of those issues exactly can be solved or fixed, it is what we call as modification, the main question is if anyone would like to modify or not worth it, because if i want to buy a higher end Newtonian with perfect design or modification i will pay much much more than what i can modify by myself, for example my 6" f/4 Newt needs modification in all points you mentioned, it will cost me nearly $250-300 for that, which is almost the cost of the scope alone i bought, but how much i will pay if i buy another brand of 6" f/4 with high quality design??? Same with my discontinued Meade 8" f/5, i bought it for about $200+139, so inexpensive that i will never think to sell it, it also needs modifications, i did with focuser and internal light leak flocking, the rest will do later and then it is very very usable and the cost isn't a big deal, but once it is done and working flawlessly, then we return back to OP question.

From the What-It's-Worth Department—

I  can only speak for the related EDGE-HD 9.25 w/ ASI2600. To the extent they are a similar combo to the EDGE 8/2600:

• Almost zero maintenance and no-fuss adjustments. Check collimation twice a year…and sometimes discover one of those was unecessary. This despite rolling up and down a steep driveway. Collimation routine is super simple and requires no accessories. Easy to do in the field while trained on a bright star.

• No star spikes, as there is no spider. The front correction lens plate seals the tube and primary off from dust.

• The ASI2600 camera is 16 bit, whereas the 585 is 12 bit…a significant difference when pushing low level signals. 16 bit will deliver less noise, better gradients, and more accurate color on dim features.

• No modification to the focuser or tube has been required to generate very nice results with the 2600, EAF, and standard guide scope/ASI174MM.

• I don't use a reducer, nor do I BIN2. Guiding is .4 to .6, which is close enough to the scope/camera .337 theoretical resolution.

Note: As suggested, the EDGE isn't finicky and is easy to use. That makes up for the 180 sec per sub. I still get plenty of photons. True, the evening is longer than that from an F2.

I have certainly seen fantastic results from both rigs you describe. While the setup and maintenance might differ, it looks like both will perform in the right hands. I do think the ASI2600 camera has a superior imaging ability (I'm a career terrestrial photographer, if that matters). Sensitive, smooth color gradients, low noise, terrific detail, and it displays subtle changes in hue very nicely.

Neither.

I use an ASI 2600 DUO on my MN65. Slightly shorter focal length (900mm) than your 10" f/4,  wider coverage with the ASI2600 instead of the 585, and tight stars (2 pixels/4 microns). Ok so it's a tad slower at f/5.

I would 100% go with the Edge HD out of those two options.

Easier to collimate by a long shot (not that a newt is hard at f/4, just, not as easy)
Less requirement to collimate (I used to collimate my f/5 newt every session, and my f/10 SCT exactly twice in 4 years of ownership) 
The IMX571 will be a far better long term purchase than a IMX585 camera in my opinion.

I will say the IMX585 is more sensitive than the 571 in Ha and SII, which will certainly help in some scenarios, but I personally wouldn't buy a budget oriented 8" f/4 newtonian that is going to require HEAPS of money invested to make it properly usable, just so I could use a camera that is slightly more sensitive.

From a speed perspective, yes, an f/4 optic is going to be notably faster than an f/10, coupled with the fact that the 585 is more sensitive than the 2600, you will have a better experience with that coupling in terms of building strong SNR in a reasonable time frame, however, for me, I would be looking at this.

4.5" APO refractor at f/7 + 585 (lets say my scope, the Askar 120APO. 120mm f/7 = 840mm focal length)
Optics are superb, and never need collimation.
Focuser is unbelievably good.
Field is incredibly flat for my full frame camera, so the 585 will not be an issue at all

You're going to have the same pixel scale again, with none of the drawbacks of the 8" F/4 newt… but you're going to be considerably faster still than the f/10 SCT. The APO will be more expensive than the 8" F/4 Newt (even after you modify it to make it work well), but the IMX585 is cheap, and will keep the cost lower than the Edge HD 8 + 2600mc.

If budget isn't a real concern, I would (and did) buy a 4.5" APO and the 2600MC and go for gold. you'll be at 0.9"/px which is more than enough resolution for ANYONE's local seeing conditions… and if you really really want a reflector for some reason, get a 10" f/8 RC and the 2600…  a little more pricey again, but at least you're looking at a big aperture, faster than f/10, sharper/flatter optics than a newt or an SCT, holds collimation like the SCT…

I wouldn't bother with a newt unless you were buying a premium newt that was built specifiically for imaging, like the Orion Optics AG8/10/12, ASA's old astrograph newts, or the Tak Epsilon/Sharpstar HNT (thought these last two are both ultra fast, wide field scopes).

Alex Nicholas:

Have any of you guys used an off axis guider at f 10? How difficult is it to find a guide star during galaxy season?

A lot of people say a lot of things about this, and I don't understand most of them to be honest.

I've been using an OAG or a dual chip camera since 2008, in every scope I've owned, from the Askar 65PHQ @ 312mm f/l, right through to the C11 XLT at f/10 @ 2800mm.

In 2009 I was using an SBIG ST10XME on the C11 at 2800mm, using the ST10's internal guide chip, through a 3nm Ha filter and VERY VERY RARELY had issues finding a guide star.. In most cases I was able to use the AO system and make corrections at 5hz (0.2s guide exposures) and during nebula season, I was usually able to get 10hz corrections. 

Guide sensors today are VASTLY superior to what was on the ST10XME, and I currently guide mostly at 0.3~0.6s guide exposures with my 840mm focal length f/7 APO and an OAG with an IMX178 and guide on between 8 and 10 stars... 

I think the issue of OAG's not finding guide stars is made out to be so much worse than it actually is, and even guiding through filters... Guiding through filters like with the 2600MM Duo or 2600MC Duo and dual NB filters is absolutely not an issue, and in fact, you'll typically get more stable guiding through a Ha filter than without it, purely because you're cutting out all the blue end of the spectrum that is more affected by seeing.

I've have just never off axis guided before and was just wondering how difficult it would be to find a guide star. I don't want to fiddle around with my camera rotation and position multiple times before the sun rises.