MAK 127 with DSLR on EQ wedged AZ GTI

[Panda Alvin]

Title is a mouthful ...

Before we all get excited - I like to point out astrophotography is not my main objective and I certainly don’t expect good pictures at all. I just want to expand my knowledge, have some hands on experience & playing around with different setups. Edit: Oh I also know the scope its a slow F/11.8 and "Making Every Photon Count" is on my to buy list.

 

I mainly plan on getting a Mak 127 + AZ GTI for visual grab and go purposes (as you may have seen me briefly mentioned in my welcome post). However, I may later on like to try an EQ wedge + DSLR to have a dabble at astrophotography, and I have some questions that comes with.

First thing on my mind – Weight - My plan is to obtain a M12 x 300mm threaded coach bolt with 1KG counter weight, attached to the AZ GTI to reduce the overall torque required.  I know this will push the mount to its 5kg limit if I had the OTA & camera on, and review on the existing tripod is not great... Would this still be ok for short exposures (even if not eq wedged ?)

Second issue – polar alignment – Unlike the Star Adventurer, it doesn’t have a polar scope (well its designed to be AZ…). However, I plan to use my phone + app as a crude alternative, and know it won’t be 100% spot on. By having it loosely “EQed”, could I get away slightly longer exposure? For example 1 minute as oppose to 30 seconds ? Or would the star trailing just bad as without the EQ wedge ?  

Also are there any other concerns I need to know about I haven’t thought of and need considering ?

Cheers

[happy-kat]

You'll need the pro version of the app to be able to use the azgti in EQ mode. I imagine the longer exposure length you mention would be possible with a camera and lens but the 127mm with the long focal length will push the demands and probably mean reduced exposure times but for planets and the Moon you would do short videos instead and wouldn't need the EQ mode or wedge.

[happy-kat]

If you don't use the wedge then with a 127mm field rotation would be very noticeable quickly as altaz tracks in tiny left right up down movements. As a rough rule 500/focal length of telescope or camera lens before star trails.

[happy-kat]

Personally I'd use the 127mm for visual then remove it and use just the camera with lens, wedge and maybe the star adventurer counter weight bar (if it fits as it can be bought on its own) . There is a member doing that/similar I'll add a link of I can find it.

[happy-kat]

Maybe this video helps.

Link here

[Panda Alvin]

1 hour ago, happy-kat said:

Personally I'd use the 127mm for visual then remove it and use just the camera with lens, wedge and maybe the star adventurer counter weight bar (if it fits as it can be bought on its own) . There is a member doing that/similar I'll add a link of I can find it.

Thanks, I will probably give this a try instead when it happens.

Having thought more about my original post, it feels like every part of the set up isn't suitable for it. Slow OTA, awful alignment, wobbly tripod ... adding all those up, I really wonder what kind of messy blob it would come out as. 

[Alien 13]

5 hours ago, Panda Alvin said:

Thanks, I will probably give this a try instead when it happens.

Having thought more about my original post, it feels like every part of the set up isn't suitable for it. Slow OTA, awful alignment, wobbly tripod ... adding all those up, I really wonder what kind of messy blob it would come out as. 

I dont think it will be all bad, the AZGTi with a Mak is a sound travel package but has its limits.

Alan

[gul1337]

I tried MAK 127 in EQ mode and clutch gave up on AZ axis. Total load was close to 5kg (finder,ASI224MC, 1.5kg counterweight). Thread on AZ tightening rod is really fine (maybe M4-5?). It got completely stripped. I did not to over-tighten the mount. ( It's hard to believe but I read the manual  ?)

After I took the mount apart ALT clutch looks much stronger/better than AZ. AZ is just small ring that is tightened. If this screw was little bigger it would probably be ok.

Maybe my unit was defective, but I would think twice about using 5kg in EQ mode. In AZ mode it worked perfect for almost half a year.

I used AZGti on AZ-EQ5 pier tripod it worked really good and stable. Until it died ?

gul1337

[Panda Alvin]

Sorry to hear your experience regarding your mount gul1337. Can't give you mine yet as I haven’t test it extensively yet with the recent weather.

I personally find the AZ movements fairly awkward on the GTI mount in general. The AZ locking screw I have needs to go further in than I like to firmly lock, and I absolutely hate attaching it to the extension pillar (still using the star adventurer tripod atm) but need to due to the fencing in my garden. The 3/8 thread that screw to the mount often comes loose if I manually rotated the mount, and as it is embedded in the tube I can’t tighten it without taking the OTA off and resetting it up.

The weight just for planetary photography is also a red flag for me now. I have recently weighed all my components and it seems it will overload if I proceed with the following set-up. So its DSLR only or I lose the counterweight and put a sandbag on the opposite side of tripod leg I suppose.

3.50KG OTA
0.45KG EOS 1000D
0.24KG Dew Shield
0.05KG T2 Ring
1.00KG Counterweight
0.24KG Counterweight Shaft
5.48KG in Total ? 

Happy-Kat, I could be wrong but I read from a forum somewhere that the star adventurer counterweight kit has a 12mm shaft but only an M8 thread, so will not fit in the mount.

[happy-kat]

Thanks for the update, noted.

I hadn't been suggesting the 127mm mak was used when trying EQ mode on a wedge it's too heavy as you've now noted.

[TheMan]

I have this mount in EQ mode and i can get some 30 seconds exposures without auto guiding and only rough polar alignment, with my Nikon d3300 and 72ed APO

 

[Panda Alvin]

 

7 hours ago, TheMan said:

with my Nikon d3300 and 72ed APO

I assume this is with the focal reducer at 357mm focal length? What did you point at and how did it go?

[JamesF]

I've used my 127 Mak with a DSLR for imaging planetary nebulae before now.  The mount does need to be pretty solid though, otherwise you end up throwing a lot of subs away.

As regards alignment, I'd probably drift align using APT or something like that.

James

[TheMan]

22 hours ago, Panda Alvin said:

 

I assume this is with the focal reducer at 357mm focal length? What did you point at and how did it go?

It has a 400 mm focal length f/5.5, no reducer (not enough money for one), i did a few tests on a few stars (Altair, Antares), for 20-30 second subs, very little to no star trails, wind did effect some tests though. Note, only rough polar alignment was used (phone planetarium app), haven't got a guide scope/camera yet for precise polar alignment and tracking. Still a newbie at this and still learning.

[ollypenrice]

On 27/09/2018 at 05:33, TheMan said:

I have this mount in EQ mode and i can get some 30 seconds exposures without auto guiding and only rough polar alignment, with my Nikon d3300 and 72ed APO

 

However, this is at a much shorter FL and lower resolution than the OP proposes.

I can't help suspecting that, since the proposed mount cannot possibly deliver tracking appropriate to the resolution of DSLR/Mak, you'd do better to work at a pixel scale which the mount will support because, if you don't, that long FL is going to reduce your field of view without resolving more detail. There is no point in this so far as I can see. Essentially this is to say I agree with Happy Kat's suggestion.

Olly