Best Apochromatic Refractor for the $$$$?

[Leveye]

I have a budget of no more than $700 american for the OTA ,the field flattener and a t-ring for the dslr camera so with that budget what would you choose? I will only be using it to image not viewing and it must be under 11 pounds total weight for the mount i have.I'd like at least 400-500mm Many thanks.

[baggywrinkle]

Reflector or refractor....400mm is 16'' or thereabouts, that is a very big refractor.

[rowan46]

It's a big ask it seems to me to get a scope, flattener and t ring for 700 dollars even in the usa where its cheaper the orion ed 80 probably comes closest to that but it only has a single speed focusser which is not ideal for photography although you would probably wish to motorise it anyway

[Leveye]

The focuser can be replaced on the Orion ED80 can it not? Crawford is the way to go i guess?

[Leveye]

Reflector or refractor....400mm is 16'' or thereabouts, that is a very big refractor.

Refractor is the way i'm going to go for sure BW i love good glass i'm a photographer first and foremost but realise a camera lens or at least what i have in that range is not going to cut it.It's a 80-400mm zoom with a teleconverter and lots of moving parts i don't want to deal with.

[Leveye]

I see the Astro-Tech AT65EDQ has a field flattener built in and is only $599 here that would leave me enough for a guide scope and camera. The prices are slowly coming down there's so much competition but good for us!

[tuckstar]

Think were talking 400-500 mm focal length not aperture.

Its a big ask to get any apo at that price even second hand. If your using for astrophotography maybe a good achro would be a cosideration. Long focal length to avoid C/A.

I'm not an expert so someone feel free to correct me.

[Adamar98]

I have the AT65EDQ. It's a fantastic little scope. A little weighty for its size but I wouldn't swap it for the world.

[Leveye]

I have the AT65EDQ. It's a fantastic little scope. A little weighty for its size but I wouldn't swap it for the world.

It's in my weight limit for my mount do you have some examples you took with it? Does the built in flattener do a good job?

[Adamar98]

If you go to the Flickr site and search either AT65EDQ or TS65Q you'll find a few examples.

[lensman57]

I have a budget of no more than $700 american for the OTA ,the field flattener and a t-ring for the dslr camera so with that budget what would you choose? I will only be using it to image not viewing and it must be under 11 pounds total weight for the mount i have.I'd like at least 400-500mm Many thanks.

Hi,

I think that you mean 400~500 mm focal length which with your budget means an ED Doublet and not an Apo as these are triplets and out of your budget range . If these assumptions are correct then you'd be looking at something about 80 mm in aperture and about F6, there are a lot of imaging scopes of this kind around from the usual suppliers and you have to do your own research as to which one is suitable for your needs. Most of these employ the type PL51 glass but I know of atleast one from Opticstar that has PL53 glass which in theory should give slightly better colour correction. If you need a scope for general observation you might want to consider a newtonian of about 5~6" aperture rather than an ED or a used APO .

Regards,

A.G

[Leveye]

Yes i meant 400-500mm in focal length at least. The AT65EDQ is advertised on Astro-Tech's site as an Apochromatic ED dual quadruplet and having a triplet objective lens...lol whatever that means just sounds better does it not?. I like this one now to find one to purchase they have been out of stock for a long time i guess that means they're selling well. As stated above it will be used only for Imaging/astrophotography to replace the telezoom camera lenses i'm using right now.

[Leveye]

https://www.astronomics.com/astro-tech-at65edq-65mm-astrograph-telescope_p18437.aspx

[Leveye]

If you go to the Flickr site and search either AT65EDQ or TS65Q you'll find a few examples.

Found nothing using the model # or brand name of it. Does the field flattener do a good job?

[Leveye]

Hi,

I know of at least one from Opticstar that has PL53 glass which in theory should give slightly better colour correction

The AT65EDQ uses FPL-53 glass in it so thats a plus.

[Adamar98]

It's called the TS65Q over here. It's a triplet with built in flattener. You'll need the 2" long t-thread to achive focus. Type either AT65EDQ or TS65Q into google images. It's a cracking scope. Images come out flatter than a flat thing that's been flattened by a big flattener! They had a few problems with the earlier models. The casing tightend to much in really cold temperatures. So be careful buying one second hand.

[Leveye]

Good to know thanks for the advice Adamar98 and yeah that sounds flat enough for me..;-)

[ollypenrice]

The focuser can be replaced on the Orion ED80 can it not? Crawford is the way to go i guess?

Crayford, not Crawford, is the way not to go! Good ones are just about OK, bad ones are the root of all evil. Rack and pinion is the best system. The budget Crayfords littering the cheaper scope market are abominable beyond description and most of them last a week before going in the dustbin. Then people upgrade them to posh Crayfords like the Moonlite, Baader Steeltrack or Feathertouch. Or you can go the extra mile and buy a Feathertouch R and P. The danger with setting a tight scope budget is that you play into the hands of the marketing men. You buy X scope because it was below Y price and then you discover that a shoddy focuser is wrecking every image. At this point you pay half the original budget for a workable focuser.

Takahashi telescopes do not have Crayford focusers. There is a reason for this...

Olly

[Erquy]

Hifo

For examples, astrobin.com, and advanced search (can find through combined scope, camera etc...)

[Leveye]

The AT65EDQ has a rack and pinion 2' focuser and 10:1 fine focuser sorry bout the typo there. Another + check on the AT buy list. Canada here has them in stock at 2 different locales and no answers from emails sent inquiring on a purchase not a good start.

[Leveye]

Hifo

For examples, astrobin.com, and advanced search (can find through combined scope, camera etc...)

Great site thank you!

[lensman57]

Crayford, not Crawford, is the way not to go! Good ones are just about OK, bad ones are the root of all evil. Rack and pinion is the best system. The budget Crayfords littering the cheaper scope market are abominable beyond description and most of them last a week before going in the dustbin. Then people upgrade them to posh Crayfords like the Moonlite, Baader Steeltrack or Feathertouch. Or you can go the extra mile and buy a Feathertouch R and P. The danger with setting a tight scope budget is that you play into the hands of the marketing men. You buy X scope because it was below Y price and then you discover that a shoddy focuser is wrecking every image. At this point you pay half the original budget for a workable focuser.

Takahashi telescopes do not have Crayford focusers. There is a reason for this...

Olly

Hi,

I only found out last night that the 3" (it is massive for an 80 mm ED scope) crayford focuser on my scope has a broken bearing ( the casing has cracked) , the bearings are 8X4X4 mm which is not an off the shelf size, I have ordered 8X4X3 mm bearings and I will have to machine some derlin washers- spacers to sort the damn thing out. What a bother. I am with Olly as far as R&P is concerned, I am in two minds to wether I should change the feeble PTFE bearings on the main shaft with proper ball race bearings while I am at it.

Regards,

A.G