TheSkySearchers

Lady Fraktor wrote: ↑Wed Nov 09, 2022 5:55 pm For visual it would likely be fine but for AP you want to stay lower in capacity.

Lady Fraktor wrote: ↑Wed Nov 09, 2022 6:16 pm The difference in focal length does not give you more 'reach', shorter just provides faster imaging time and a slightly wider FOV.
Mounts are the most important part of your setup be it visual or AP.
Under mounting can work but may lead to frustration whereas over mounting is always preferable for a solid setup.

hatflyer wrote: ↑Wed Nov 09, 2022 6:20 pm The longer the focal length the more distant the objects u can image, right? So a loss of 130mm is notable, yes?

JayTee wrote: ↑Wed Nov 09, 2022 10:03 pm If you get heavily into AP, then we will get into the war of f/ vs FL. Considering one over the other has both pros and cons. We'll worry about that once you start imaging.

I'm firmly in the FL camp because ignoring it has way more implications than ignoring f/. Also, FL determines which equipment to use way more than does f/ alone!

Additionally, the rule of thumb for AP load on any given mount is 50-60% of the max rated load.

hatflyer wrote: ↑Wed Nov 09, 2022 10:10 pmSo looking for the most possibilities in capturing DSO.

JayTee wrote: ↑Thu Nov 10, 2022 12:52 am Any aperture can be made smaller (but we don't want that). What you can't do is make it larger. A 102mm objective can never be bigger than 102mm. But FL is completely variable with reducers and focal extenders (like a barlow). FL determines image size for any given sensor. So we consider the Aperture and the sensor size as fixed. Realistically ALL we can vary is the FL

hatflyer wrote: ↑Wed Nov 09, 2022 10:10 pmSo looking for the most possibilities in capturing DSO.

Your greatest success with limited funds is a DSLR (with a 50 to 400mm lens) on an inexpensive EQ mount. Many great images on these forums were acquired using that gear.

Even something as inexpensive as this. Before you read this article skip down to the images first.
viewtopic.php?t=3129

SkyHiker wrote: ↑Wed Nov 09, 2022 6:53 pm The standard rule of thumb is a factor 1/2 so a 5.5 lbs. limit for AP if a visual load of 11 lbs. is advertised.

A difference of 130 mm is definitely noticeable but it's not the only factor. For AP of DSOs you should look at the F ratio not the focal length. It determines how much integration time you need. For AP of planets you need large aperture (ideally say, 14") and exceptionally good seeing like once in a year or so. With less good seeing, 6" or 8" aperture will do fine. Smaller aperture works too but the resolution will be noticeably limited by the aperture not just the seeing.

hatflyer wrote: ↑Thu Nov 10, 2022 3:40 pm

SkyHiker wrote: ↑Wed Nov 09, 2022 6:53 pm The standard rule of thumb is a factor 1/2 so a 5.5 lbs. limit for AP if a visual load of 11 lbs. is advertised.

A difference of 130 mm is definitely noticeable but it's not the only factor. For AP of DSOs you should look at the F ratio not the focal length. It determines how much integration time you need. For AP of planets you need large aperture (ideally say, 14") and exceptionally good seeing like once in a year or so. With less good seeing, 6" or 8" aperture will do fine. Smaller aperture works too but the resolution will be noticeably limited by the aperture not just the seeing.

I found a scope that is only 4.1 pounds (the Tecnosky APO 70/420 , f/6). Compared to my current set-up, with my camera 400mm, this would add only 1.5 pounds. And be the same focal length. So if it works with my camera lens, this 7.2 pound load may work as well?

SkyHiker wrote: ↑Thu Nov 10, 2022 4:45 pm

hatflyer wrote: ↑Thu Nov 10, 2022 3:40 pm

SkyHiker wrote: ↑Wed Nov 09, 2022 6:53 pm The standard rule of thumb is a factor 1/2 so a 5.5 lbs. limit for AP if a visual load of 11 lbs. is advertised.

A difference of 130 mm is definitely noticeable but it's not the only factor. For AP of DSOs you should look at the F ratio not the focal length. It determines how much integration time you need. For AP of planets you need large aperture (ideally say, 14") and exceptionally good seeing like once in a year or so. With less good seeing, 6" or 8" aperture will do fine. Smaller aperture works too but the resolution will be noticeably limited by the aperture not just the seeing.

I found a scope that is only 4.1 pounds (the Tecnosky APO 70/420 , f/6). Compared to my current set-up, with my camera 400mm, this would add only 1.5 pounds. And be the same focal length. So if it works with my camera lens, this 7.2 pound load may work as well?

The price is low, the weight is probably as low as it gets but still above the 5.5 lbs. rule of thumb. It may or may not work, all I can say is just that.

See if you can find out if a flattener is needed. For instance, if you look at the Sharpstar 61EDPH they warn that a reducer/flattener is needed for AP. Now, that scope is F/4.5 so maybe F/6.6 is forgiving enough to get by without. Maybe Jim (Juno16) can weigh in, he has one of those and takes fabulous images with it. Of course, he uses an autoguider.

If you want to take the guess work out, strap a 1.5 lbs. weight on to your camera and see if it can deliver pinpoint stars. One more thought, I don't know what DSLR you have but a mirrorless DSLR like a Fuji X-a1 or X-a2 body can be had on EBay for $130 or so. I have used an X-a1 myself, it works quite well, and those cameras are lighter than a regular DSLR.

Lady Fraktor wrote: ↑Thu Nov 10, 2022 9:08 pm The Celestron CG-4 or Skywatcher EQ-3/2 (same mount and company just different name)
https://www.astronomics.com/celestron-o ... mount.html
https://www.firstlightoptics.com/equato ... eluxe.html
They are rated at 20 lb capacity.
Both are manual mounts but tracking motors are available as well as a goto kit.
https://www.firstlightoptics.com/sky-wa ... is-dc-moto
The goto kit has to be ordered from UK/ EU as it is not available in USA.
https://www.firstlightoptics.com/sky-wa ... eq3-2.html

The only big difference between the two is that the Skywatcher comes with a aluminium tripod whereas the Celestron has a steel tripod.