Question about trackers...

Hi, I know very little about astrophotography so please be gentle with me...
Are star trackers only designed to be used with shorter focal length lenses or is it possible to get ones that will handle the weight of heavy lenses like the 500 f4 ??

don1163 wrote in post #17818804
Hi, I know very little about astrophotography so please be gentle with me...
Are star trackers only designed to be used with shorter focal length lenses or is it possible to get ones that will handle the weight of heavy lenses like the 500 f4 ??

Heya,

There are different trackers. There are inexpensive "for small kit" trackers, in the $300~400 range. There are trackers for serious lenses and big telescopes that start in the $1k area for proper EQ mount trackers. A 500 F4 is not something I'd put on one of the smaller "for small kit" trackers (like the iOptron, Sky Adventurer, Polarie, Astrotrac, etc). That size lens would really need to be on a very stable and high payload tracker to get anything good out of it (it has to be very, very stable to get a long exposure at that focal length, at that weight, and I'm talking 60 seconds or greater). For that quality lens and that weight, I'd be looking at a very good EQ mount (like a Meade; or German EQ), $750~$1k starts that. If you want to stay in the $300~400 range, you'll need to stick to shorter, lighter lenses. You can do 200mm~300mm pretty easily on the smaller trackers and get good 60~90 second exposures with very little alignment (I've done 90 seconds with 180mm on APS-C with no specific alignment just fine on an iOptron). But 500mm F4 weight wise, I would not put on one of these little trackers, even if the weight limit is met. It will not be stable and it will not get a clean, sharp image for 60+ seconds.

So it comes down to your budget, and what you want to capture and how long of exposures you think you'll be doing.

Very best,

Many thanks for explaining things to me...I now have a better idea of things..

don1163 wrote in post #17818834
Many thanks for explaining things to me...I now have a better idea of things..

Heya,

To further give you some things to consider:

Entry for smaller kit:

SkyWatcher Star Adventurer. In the tier of entry budget, and sticking to shorter lenses (200mm~300mm, you could probably squeak more out, but I'm talking safely considering without ultra careful setup in the field in non-ideal conditions which is the most common thing you'll experience), shorter scopes, and of course all the wide field you could want, holds 11lbs payload which is important and quite a bit more than what the other options in the same price range can do (they top out around 7lbs). This would be a great solution to get out and do long exposure (4 minutes is easily possible) with a dSLR and lens upwards of 200m~300mm, better of course with slightly shorter lenses. I'd get this over the iOptron and Polarie systems in a similar price range. Around $500 is expected for this, and it's really meant for small kit but it's easy to use and relatively small & light weight to carry.

Star Adventurer (link)
Wedge (highly recommended)(link)
Counter weight (highly recommended)(link)

A step up entry option, if you want a lot more weight capacity, good tracking, and be ok with aligning and not having a "Go To" option. Pretty reasonable, takes upwards of 20lbs, so it's a generous step up from dSLR focused kit. This was meant for smaller scopes and use with cameras. Tracking is good. Reasonable in the $550ish range new. It's only a little more than the above option, but it's heavy, and takes a bit more to get it doing what you want it to do, and will take more accessories to really get it doing long tracks with long lenses (you will need to align). Still great option if you don't mind weight, if you want to keep it on a budget.

Orion SkyView Pro
TrueTrack drive for the SVP for tracking

Entry for middle of the road, something not outrageous, but capable of serious tracking (10 minutes easy) with big lenses or scopes. The Orion Atlas EQ-G. It's not cheap. But it's something that will not hold you back if you want to use larger lenses or longer larger scopes either. Payload is big, 30lbs big, and the tracking is very good, again, you can get 10 minutes on this fairly easily with a little alignment setup time (10~20 minutes depending on your experience). This is what I would suggest in terms of getting something powerful for big lenses, but reasonably priced, that will not hold back your abilities with the gear you've described. Granted, this is the $1500 range.

Orion Atlas EQ-G (link).

Entry for larger kit, and much higher quality, for more serious level stuff and observatory level stuff:

Here's the Losmandy HM8, EQ tracker/mount. This is more serious and will take a lot more weight. It'll handle the 500 F4L, but more importantly, it will handle more serious telescopes if you need more reach for DSO's and the like. This obviously isn't for entry, but it is entry for serious trackers in this weight payload tier. The high quality stuff easily gets into the $8k+ range which is nuts, but those are for people with personal observatories. This is more still suituiable for someone just going out some where with some dark skies with a heavy setup and doing some longer exposures with telephotos that are heavy. Still not cheap, but again, this is entry into the more serious tracker world. This easily gets $2k+.

http://www.losmandy.co​m/gm8.html

Very best,