Skymax 102+AZ Gti + modified canon 1200d - what mounts, spacer, focal reducer ?

[powerlord]

Hi chaps,

beginner here.

er I AM trying to learn all the techie stuff as quick as I can, but it is a deep learning curve.

I've been having a lot of fun with my 102 (1300mm) looking at the moon and especially M42. I designed and printed a 3d printed mount solution for EPs and my phone that let me shoot pretty good pics with my EPs and it's got me a taste of AP.

So - I know it's far from ideal OTA for DSO but.. it's what I've got for now. I've ordered a modified canon 1200D.

And I'm now a little bit confused as to what I need to mount it, and whether I need a focal reducer.

the outside thread on the OTA is a 42mm thead I think. So I need a canon t-mount I assume.

Does it need a spacer ? Are spacers all the same size ?

And, how do I calculate the fov I will get with that ?

If I need a focal reducer, I assume this screws into the interior OTA thread, and since this is quite deep, I assume it's trial and error getting this to the right point ? (55mm is mentioned some places)

And then just a matter of getting a 1.25 0.5 or 0.5 reducer and screwing it in ?

I realise I'm going to be doing 30 second odd exposures here to get anything decent, and it would be better with an EQ mount, and a different OTA, etc, etc - but that can all be added to later - just wanna expand out and enjoy for now.

all advice appreciated - I'm enjoying this new hobby far more than I thought I would to be honest - first time I captured M42 I couldn't believe what I was seeing !!!

stu

[vlaiv]

You only need Canon T ring.

It screws directly into visual back end of the scope - it has T2 thread on it.

There is no suitable reducer for this combination - and it would not work properly anyway because Mak can illuminate only about 26mm diameter and I'm guessing that Canon 1200D is APS-C sized sensor with 28mm. You will get some vignetting as is and you'll need flat fielding.

Dew shield is a must on that scope - and not because of dew - but because of the way it is baffled internally - not very good, so you need to make sure you have stray light protection.

You can convert AzGTI to EQ type mount - and I would recommend that. With such long focal length, you will be sampling at high sampling rate - so you'll need to bin your data to get anything decent.

Although your camera is 6000x4000 px - in reality, you'll be getting images that are 1500x1000 or even 1000 x 666 - if you want to get decent images with this scope. This all means that you need very long exposure images - at least couple of minutes to minimize impact of read noise. That in turn means EQ type mount.

AzGTI can be turned into EQ mount - you'll need counter weight and shaft, and EQ wedge - look up on SGL there are couple of threads discussing how it is done.

You'll also want to guide because AzGTI is not very precise mount - and even with guiding - don't expect very sharp results. AzGTI is very basic mount capable of only low resolution (usually wide field - but with your scope that is not going to be wide field by any account).

Go to astronomy tools and check FOV of your scope - use 1300mm of FL if Skymax 102 is not in equipment database.

It appears that SkyMax is indeed in equipment database and so is Canon 1200D

it also says that 1200d is not 6000x4000 - but you get the idea, even with smaller pixel count, you'll still have to bin at least x4

[The Lazy Astronomer]

Do yourself a favour and just use your camera lens. Long focal length maks are not recommended for DSOs.

Alternatively, l recently saw a thread from a guy who was trying imaging using eyepiece projection with a mak and DSLR, maybe search for that and see how he got on?

P.s. Welcome! ☺

[powerlord]

Thankyou for the advice - greatly received. I see the DLSR as a way of just getting used to it a bit, then maybe I get a second OTA.

I've shot with my polarie and Sony RX10iii (600mm) and got some decent (well, i'm happy..) M42 shots and will continue to do that for sure.

I thought maybe with the DSLR I'd get a bit better than I'm getting currently through the OTA with my mobile ? Or will they be much the same then ?

Attached 1 shot via the sony, and one with the mobile (and x54 EP)

I realise compared to the amazing pics on here these are terrible - but I enjoy taking them 🙂

this is telescope and mobile (x54):

this is sony at 600mm on polarie

Edited February 4, 2021 by powerlord
descriptions

[vlaiv]

1 minute ago, powerlord said:

I realise compared to the amazing pics on here these are terrible - but I enjoy taking them

I'm sure that with DSLR you'll be able to take at least as good images as those.

Do remember that due to long focal length and need for tracking - you'll need special kind of processing step - binning your data after stacking.

There are couple of software solutions capable of doing this. I personally use ImageJ - which is free software package that runs on Java for this.

[powerlord]

thanks - I'll look up that program. I've been faffing with deepskystacker using crossover (Im on a mac), but struggling to get it to do much. Enjoying learning - but jeez it's a steep learing curve.

[powerlord]

So chaps, if I was to 'invest' another whack of cash at this (ideally no more than 500 quid), I'm assuming a motorized EQ mount and an F5 or so newtonian would be the sort of thing to stick my 1200d on the end of ?

Would a celestron astromaster 130eq motorized work ?

Or would it be best getting more light via something like a skywatcher explorer 200p now on my az GTI , and saving for a decent EQ mount later (like an EQ3 ) ?

[vlaiv]

55 minutes ago, powerlord said:

So chaps, if I was to 'invest' another whack of cash at this (ideally no more than 500 quid), I'm assuming a motorized EQ mount and an F5 or so newtonian would be the sort of thing to stick my 1200d on the end of ?

Would a celestron astromaster 130eq motorized work ?

Or would it be best getting more light via something like a skywatcher explorer 200p now on my az GTI , and saving for a decent EQ mount later (like an EQ3 ) ?

AzGti will not hold 130PDS properly for imaging let alone 200mm scope. Eq3 is not decent mount for imaging.

If you want to get different setup - look into at least EQ5 class mount as starting point and scope like 130PDS or 150PDS - forget 200mm scope for now.

[The Lazy Astronomer]

Yeah unfortunately, astrophotography is not cheap. The general advice is the most important thing is the mount and this is where you should put most of your money. For a proper mount, you're looking at £700+, less if you can find one used.

A lot of deep sky objects are BIG, so you don't need a large telescope to image them. This is why l say stick to lenses, preferably widefield ones. You could then get away with using your current equipment for a while. Then, if you haven't thrown all your gear off a bridge due to the insane number of frustrations encountered in this hobby, you can look at upgrading equipment.

If you really wanted to use the mak, it would be well suited for the moon and planets (although you'll have to wait a few more months for Jupiter and Saturn to come back around).

[powerlord]

Yeh I'll def keeping using the mak for now. and unsuited as it is - I'll still enjoy using it with slr and phone.

I'm definately interested to see what affect the full spectrum modifications on the SLR make too.

And keep using my Polarie with my Sony RX10mkiii which is a damn fine camera

Seems to me like any other hobby - you can game on a 500 quid laptop, you can gain better on a 2000 quid tower PC, and there's always something better for 5000 quid, etc. 🙂

stu

[AstroNebulee]

They are great images for a first time something to be proud of. It's all about the enjoyment you get when take your first images, don't push yourself to hard and try not to run before you walk. Learn your equipment and processes. With your new modded Canon 1200d you could try dslr wide field imaging on your az gti see what results you get as there are spectacular wide field views out there especially with a modded dslr. You can get some longer exposures with a dslr lens even a stock one. This is from my unmodded Canon 450d and stock 18-55mm lens, of just above Orion, not brilliant I know but the mw & pleiades is there and you can get some cracking images, clear skies 

Edited February 6, 2021 by LeeHore7

[vlaiv]

This topic should be of interest:

It shows that with a bit of care - AzGTI can guide in 1" - 1.5" RMS range without much issues.

It is general rule of the thumb that guide RMS should be at least half of the sampling resolution - which gives us baseline for imaging resolution on this mount. I'd say that 3"/px or above is doable.

I'm still talking about using SkyMax102.

Canon 1200D has ~4.3µm pixel size. Base resolution is 0.68"/px. If using super pixel mode (and one should) that is doubled to 1.36"/px. Doubling that by binning x2 - will not be enough in my opinion as it will end up at 2.72"/px, but using x3 binning will be just right at 4.08"/px

This means that image will be only 864 x 576 in the end, but mosaics are always an option.

[Newforestgimp]

Hi There,

I wont offer tech advice as I'm learning myself, but what I would say is save yourself some pain and decide on visual or AP from the outset, then go from there> the guys on here have helped me enormously and I quickly gave up any ambitions of combining two aspects with one set of kit. I decided to go the AP route and have started small to learn the craft, WO Z61 with an EQ35-M pro and DSLR, all I can say is from my brief experience the Z61 is a joy to use, the EQ35-M is beefy enough for my ambitions currently, has a 10kg Payload so i have a bit of 'scope' for enlarging the OTA at some point, and has better gearing than the EQ3-PRO and Eq5-PrO i believe, its modular so can double as a camera basic star tracker too. I've also enjoyed just sticking the DSLR on a weighted tripod with ball head & an 18mm kit lens and just popping away with 20 second or so exposures.
I would only buy gear that you think will be of use long term TBH and I know that a small Refractor will always be in the quiver, its just so versatile for photography.

[powerlord]

8 hours ago, vlaiv said:

It shows that with a bit of care - AzGTI can guide in 1" - 1.5" RMS range without much issues.

It is general rule of the thumb that guide RMS should be at least half of the sampling resolution - which gives us baseline for imaging resolution on this mount. I'd say that 3"/px or above is doable.

I'm still talking about using SkyMax102.

Canon 1200D has ~4.3µm pixel size. Base resolution is 0.68"/px. If using super pixel mode (and one should) that is doubled to 1.36"/px. Doubling that by binning x2 - will not be enough in my opinion as it will end up at 2.72"/px, but using x3 binning will be just right at 4.08"/px

This means that image will be only 864 x 576 in the end, but mosaics are always an option.

I won't lie and say I followed any of that 🤪

but as the saying goes - best camera is the one you've got.

[powerlord]

6 hours ago, Newforestgimp said:

Hi There,

I wont offer tech advice as I'm learning myself, but what I would say is save yourself some pain and decide on visual or AP from the outset, then go from there> the guys on here have helped me enormously and I quickly gave up any ambitions of combining two aspects with one set of kit. I decided to go the AP route and have started small to learn the craft, WO Z61 with an EQ35-M pro and DSLR, all I can say is from my brief experience the Z61 is a joy to use, the EQ35-M is beefy enough for my ambitions currently, has a 10kg Payload so i have a bit of 'scope' for enlarging the OTA at some point, and has better gearing than the EQ3-PRO and Eq5-PrO i believe, its modular so can double as a camera basic star tracker too. I've also enjoyed just sticking the DSLR on a weighted tripod with ball head & an 18mm kit lens and just popping away with 20 second or so exposures.
I would only buy gear that you think will be of use long term TBH and I know that a small Refractor will always be in the quiver, its just so versatile for photography.

 

very nice, and food for thought. I'll stick with what I've got for now. As you say - learn to walk. I've got wide field options with the 50mm prime on the modified 1200d, and wide or zoomed with the RX10. Both could be on the gti mount, but probably better on the Polarie, except up towards 600mm on the RX10 in which case the GTI is worth a try.

And for all the tmount cost, its worth a try too to see what it can do on the skymax.

I might post some pics and video of what I've designed there for my mobile mount - took me a while to get right but now it's just plugin and go and works well too.

thanks for the advice chaps.

 

[Newforestgimp]

14 hours ago, powerlord said:

I might post some pics and video of what I've designed there for my mobile mount - took me a while to get right but now it's just plugin and go and works well too.

I’d be interested in seeing the 3D printed item, sounds useful 👍

[powerlord]

On 07/02/2021 at 09:22, Newforestgimp said:

I’d be interested in seeing the 3D printed item, sounds useful 👍

I've posted a video here:

 

 

 

[Newforestgimp]

Very cool, 3D printing always amazes me. Such a handy little jig for the phone too.