SW ED 80, 100, 120, Triplet, or ...?

[Wescombe]

Hi all,

Newish here and looking at getting in to Astrophotography. I've recently bought some Apollo 15x70's to get started with and learn the sky a little more etc but I'm planning ahead for AP already

I was emailing Steve at FLO for a little while but wanted to gather some additional opinions.

I was originally looking at the ED80 with EQ5 mount, seemed quite reasonable, then thought maybe I should get the NEQ6 mount to future proof myself and heard that with a full AP setup it may struggle. So because there isn't a bundle I was looking at the ED100 as it would be the same price as the ED80 after buying the additional focal reducer.

After reading some more posts etc I'm now thinking maybe the ED120 due to its lower f number and getting the reducer on it (I assume its required). Or should I consider something like the ED80 Triplet (similar price range to the ED120), pay a bit more for the ED100 Triplet, or is there a different type of scope altogether to maybe consider instead?

Is it really better to go for the lower f number than the larger diameter?

Appreciate any thoughts and thanks in advance.

Paul

[Wescombe]

Forgot to add, for the moment I will be planning on using a DSLR to go with this setup. Nikon D7000 for reference.

[Bizibilder]

I think you will find spending around £20 on "Making Every Photon Count" (by Steve Richards - available from FLO) would be a very good investment before you start out, it gives sound advice and tells you what the pitfalls are. (usual disclaimer).

[ronin]

The larger the diameter then, in general, the greater amount of CA and SA will be present.

The spherical shape of the lens surface is not correct, and at the edges it is worst.

An ED is still a doublet, immaterial of the glass used in its construction. It place 2 wavelengths on the same focal plane.

The faster the lens then the harder it is for the glass to be designed to compensate for the aberrations. There was a time when manufacturers made quite a few fast lens in triplet and ED format. These are now increasingly rare as they make slower lens that are easier.

There is really no golden rule.

Going down the "fast" route is one option that many follow.

However "fast" is a photographic term and although you are photographing things the differences are enormous. Simply start is in AP the exposures are not 1/250 second and you do not need to track a landscape. However like AP a good fast camera lens can be a few thousand pounds.

Do not get the bit that an EQ6 may struggle with a full AP setup, have seen a number of AP setup's on EQ6 's and no mention of a struggle. You might struggle to move an EQ6 but the mount I doubt will struggle.

Back to the scope. It reads that you are thinking that bigger is better?

First rule is do not consider visual requirements when choosing an AP setup.

If you want to do AP and you have the choice of a good 80mm triplet or a good 120mm ED then I would go for the 80mm triplet.

Not common here but WO have a "new" GTF-81 out, they also have a GTF-102. Both have a built in flattener, which I believe will make the scope slower. I think the GTF-81 goes from f/5.9 to f/6.3 or something close. There is equally the question of is a seperate flattener better as you can adjust it. Also the flattener is not a reducer.

[lensman57]

Hi all,

Newish here and looking at getting in to Astrophotography. I've recently bought some Apollo 15x70's to get started with and learn the sky a little more etc but I'm planning ahead for AP already

I was emailing Steve at FLO for a little while but wanted to gather some additional opinions.

I was originally looking at the ED80 with EQ5 mount, seemed quite reasonable, then thought maybe I should get the NEQ6 mount to future proof myself and heard that with a full AP setup it may struggle. So because there isn't a bundle I was looking at the ED100 as it would be the same price as the ED80 after buying the additional focal reducer.

After reading some more posts etc I'm now thinking maybe the ED120 due to its lower f number and getting the reducer on it (I assume its required). Or should I consider something like the ED80 Triplet (similar price range to the ED120), pay a bit more for the ED100 Triplet, or is there a different type of scope altogether to maybe consider instead?

Is it really better to go for the lower f number than the larger diameter?

Appreciate any thoughts and thanks in advance.

Paul

Hi Paul,

As a relative newcomer myself I would like to make you aware of a few points.

First you should decide from the onset what kind of imaging you want to do. Planetary imaging needs a different set of hardware than a widefield DSO or galaxy imaging.

The next point is that the most important link in the chain is the mount. EQ mounts are the order of the day and the choice of the mount will to a extent  dictate what kind of scope you can use.

The choice of the SW ED 80 and an HEQ5 pro is almost like the universal choice for starting the widefield imaging, not much good for planetary though as you need a long focal length scope for this, SCTs do well here.

I have the SW 100 DS PRO with the reducer but I use it more of a planetary scope than a widefield, it is also a bit on the slow side @F9, F7.7 with reducer. The ED 80 is F7.5 and F6.4 with the reducer so it is faster and wider than the DS PRO.

There are a lot of points to consider including the choice of the imaging camera, possible guiding hardwareand so on and you need to do a lot of research before parting with money.

A.G

[Alveprinsen]

To add some quick perspective here...

I'm using an Evostar 80ED Pro, and it delivers kickass results. If I had used a field flattener for it, the results would be even more kickass.

I am also using a NEQ6 Pro mount, which is equally kickass, but I bet you could do a pretty damn good job with an EQ5 too.

And I am using a Skywatcher Startraveler 102/500mm with an Orion starshoot autoguider for guiding the mount, which works like a charm. side-by-side guiding in a dual dovetail saddle... Potentially theres like no limits to the exposure-time thanks to spot-on guiding... but there's noise, and over-exposure.. so... yeah..

If you invested in a similar setup, the weakest link would be your camera, however expensive it is. After a season (or possibly less) you would quite likely be looking for a modified DSLR after realizing the CCD cameras will deliver nothing in the vicinity when it comes to chip size... They might be more sensitive, but the tradeoff for increase in sensitivity vs. absolutely insane decrease in chip size simply isn't worth it... at least in my opinion...

If you want to do planetary imaging, a long focal length Maksutov telescope or a Schmidt Cassegrain will do the job for you, along with either a dedicated CCD camera, OR a modified web-camera... Downside with that is, you're limited to looking the few planets in our modest solar system... Once that is done.. nothing left but the nebulae, star-clusters, galaxies... etc. etc., which requires a faster and wider field scope. Or long focal length fast F ratio scope at an insane price.

I got a Skywatcher 180 Pro Maksutov collecting dust down in the observatory right now. Planning on imaging Jupiter with it later this year or perhaps after newyear... But the 80ED Pro is constantly in use. So many shiny things out there to image...

so there ya have it.

[John]

Don't know much about imaging but I believe the ED Pro range and the Equinox range are ED doublets while the new Esprit range are triplets.

[Wescombe]

Thanks for some of the feedback guys. I was looking at getting that book as I've heard its pretty much the go to resource. Was considering more DSO than planetary and sorry I meant that I had heard the EQ5 can struggle, I've read the NEQ6 is sound for AP.