Oag with Nikon DSLR

[SteveBz]

Hi Guys,

I'm thinking of getting an OAG. The problem seems to be that if I want to continue to use my coma corrector, the OAG needs to replace my t-Ring. Sadly all the OAG plus thin adaptors seem to be for Canon Eg TOAG. I did find a 1 mm thin adaptor for Nikon on Aliexpress, but sadly it has the wrong m42 thread  (1mm instead of 0.75).

Any thoughts?

Regards

Steve

[Robindonne]

There must be other thin adapter options.  I also use a 1,5 mm eos/t-ring   And it has a normal thread i quess

[SteveBz]

1 hour ago, Robindonne said:

There must be other thin adapter options.  I also use a 1,5 mm eos/t-ring   And it has a normal thread i quess

But eos is Canon I think. I do also have an old Canon 350d, which I could back up to. I don't know whether that's better or stick with the Nikon D500, wwhich at least has live view, not that I use it much any more.

Regards

Steve.

 

[Kiwi_Brad]

Hi guys

 

Does anyone have a solution for OAG with a Nikon DSLR. Seems like a better option if I could make it work than buying a new guide scope plus would reduce some mount weight. 

Nikon D5600 with a sky watcher 130pds using a baader cc.

Thanks

[SteveBz]

4 hours ago, Kiwi_Brad said:

Hi guys

 

Does anyone have a solution for OAG with a Nikon DSLR. Seems like a better option if I could make it work than buying a new guide scope plus would reduce some mount weight. 

Nikon D5600 with a sky watcher 130pds using a baader cc.

Thanks

Hi Brad,

I never saw this when I was looking, but I guess this would do the job.  I don't know if you can get if in NZ.  Also it looks a bit shiny, but this is what you are looking for.

DSLR to T-thread(F) Low Profile Adapters. (opticstar.com)

Or this one:

Artesky Low Profile 42mm T Ring for Nikon F-Mount SLR/DSLR Cameras # T2-NIKON-LOW (agenaastro.com)

There are lots on AliExpress, but they have a 1mm thread not the .75mm t=-thread that you need.

I thought there was a black one from a European supplier (Baader or TS-optics) for about 30 euros, but I can't find it now.

In the end I upgraded to a Canon 450D because it would give me the temperature of the exposure too.  Total cost:

StarPal OAG, AliExpress: £60-ish

QHY 5L-ii mono cam, AliExpress: £100-ish

Canon 450d, Ebay: £80-ish

C-CS adaptor for OAG: £5 (it needs an extra few mm and then reaches focus without any fiddling).

BTW the focus point for Canon and Nikon are about 2mm different.  You'll need the spacer, which I think is provided, or maybe the low-profile t-ring is thicker.

The only thing I would say is that I get a lot of fixed pattern noise from the Canon and if I'd had the cash I might have used the ZWO ASI 290 mm-s, it seems to be a lot more sensitive.

Hope that helps, 

Steve.

 

[michael8554]

Your Nikon back focus is 46.5mm.

Add an 11mm thick  48mm T ring

Equals 57.5mm.

MPCC MkIII backfocus to M48 is 57.5mm.

Then add OAG to MPPCC.

Does that work ?

 

[SteveBz]

50 minutes ago, michael8554 said:

Your Nikon back focus is 46.5mm.

Add an 11mm thick  48mm T ring

Equals 57.5mm.

MPCC MkIII backfocus to M48 is 57.5mm.

Then add OAG to MPPCC.

Does that work ?

Nice answer but wont the stars at the edge (where the OAG mirror picks off) still have coma?  It's hard enough to find a star anyway even without coma.  You don't want OAG stars with coma.  The thin OAG (TOAG) has a thickness of 11 mm for exactly this reason, so it substitutes for the T-ring.

[Davey-T]

2 minutes ago, SteveBz said:

You don't want OAG stars with coma.

Doesn't bother PHD.

Dave

[endless-sky]

On 16/06/2020 at 15:24, SteveBz said:

I did find a 1 mm thin adaptor for Nikon on Aliexpress, but sadly it has the wrong m42 thread  (1mm instead of 0.75).

Might this - T2-NikonS - work?

[SteveBz]

2 hours ago, Davey-T said:

Doesn't bother PHD.

Dave

Hi Dave,

What you say is true for bright stars, but for me with a QHY 5L-ii, having to choose between one or two faint stars that are almost not there, coma spreads the limited light available over a larger area and makes it even harder to find that star.  It's OK around the milky way plane where there are always plenty, but well away from the galactic plane, I find it hard to find stars.  You might point out, rightly, that focus too, shouldn't really worry PHD, but for the same reason, stars just disappear into the blackness if I don't get the focus just so. 

Kind regards,

Steve

[alacant]

13 minutes ago, SteveBz said:

hard to find stars

Does the QHY have a firmware bin? Our zwo120 clone has a 2x bin giving 640x480 which is fine. Even with our 6" f8.

Cheers

 

[SteveBz]

5 minutes ago, alacant said:

Does the QHY have a firmware bin? Our zwo120 clone has a 2x bin giving 640x480 which is fine. Even with our 6" f8.

Cheers

 

I did try the PHD2 binning, and I thought maybe it helped.  Then I forgot to check after a PHD2 crash and I later found it had reset and lost the binning.  Is there a difference between firmware binning and PHD2 binning?

Steve.

Edited December 28, 2020 by SteveBz
typo

[michael8554]

My OAG is AFTER the DSRL + MPCC, so that I can match the long guidecam light path caused by a Helical Focuser.

No choice, stars are coma shaped, but PHD2 guides sub 1arcsec just fine.

2 minutes ago, SteveBz said:

I did try the PHD2 binning,

Not 100% sure, but I believe the Binning selection in PHD2 is to indicate that Binning has been selected in the guidecam driver.

Michael

[Davey-T]

22 minutes ago, SteveBz said:

Hi Dave,

What you say is true for bright stars, but for me with a QHY 5L-ii, having to choose between one or two faint stars that are almost not there, coma spreads the limited light available over a larger area and makes it even harder to find that star.  It's OK around the milky way plane where there are always plenty, but well away from the galactic plane, I find it hard to find stars.  You might point out, rightly, that focus too, shouldn't really worry PHD, but for the same reason, stars just disappear into the blackness if I don't get the focus just so. 

Kind regards,

Steve

Hi Steve, I had similar problem when imaging out of the Galaxy with my 10"SCT using an Orion Starshoot , same sensor as QHY5, had to buy a Loadstar X2 which improved the situation somewhat, still have to rotate the main camera at times to find a guide star.

Dave

[SteveBz]

3 minutes ago, michael8554 said:

My OAG is AFTER the DSRL + MPCC, so that I can match the long guidecam light path caused by a Helical Focuser.

No choice, stars are coma shaped, but PHD2 guides sub 1arcsec just fine.

Not 100% sure, but I believe the Binning selection in PHD2 is to indicate that Binning has been selected in the guidecam driver.

Michael

Oh wow.  I did think about fitting a helical focuser.  In the end I just went with the allen keys, which are a bit of a nightmare, but sort of work.  I often think should I spend another precious night fiddling with the focus and then decide against it.  Maybe I should have gone with the helical focuser.

Steve

[michael8554]

I even tried measuring the guidecam height with digital calipers in an attempt to make tiny changes, but only a helical focuser gave best focus - with the commensurate spacing problem on the main imaging path I mentioned.

Michael

Edited December 28, 2020 by michael8554

[SteveBz]

13 minutes ago, michael8554 said:

I even tried measuring the guidecam height with digital calipers in an attempt to make tiny changes, but only a helical focuser gave best focus - with the commensurate spacing problem on the main imaging path I mentioned.

Michael

Yeah, I sympathise.  There is no really correct answer unless you shell out wads of cash.

Steve.

[SteveBz]

2 hours ago, michael8554 said:

Not 100% sure, but I believe the Binning selection in PHD2 is to indicate that Binning has been selected in the guidecam driver.

Just checked this.  On my camera binning's only available when the camera is connected.  I've just set it and created a dark library.  Let's see what happens.

Steve.

[Kiwi_Brad]

15 hours ago, michael8554 said:

Your Nikon back focus is 46.5mm.

Add an 11mm thick  48mm T ring

Equals 57.5mm.

MPCC MkIII backfocus to M48 is 57.5mm.

Then add OAG to MPPCC.

Does that work ?

 

This is the set up exactly as I have it now. Are you guys suggesting to put the OAG before the CC? 
 

would be interesting to get the thin adapter and a thin OAG then I just space it out to hit the 57.5 as required by the MPCC? 
 

I’m confusing myself here...

[Kiwi_Brad]

On 28/12/2020 at 00:03, SteveBz said:

Hi Brad,

I never saw this when I was looking, but I guess this would do the job.  I don't know if you can get if in NZ.  Also it looks a bit shiny, but this is what you are looking for.

DSLR to T-thread(F) Low Profile Adapters. (opticstar.com)

Or this one:

Artesky Low Profile 42mm T Ring for Nikon F-Mount SLR/DSLR Cameras # T2-NIKON-LOW (agenaastro.com)

There are lots on AliExpress, but they have a 1mm thread not the .75mm t=-thread that you need.

I thought there was a black one from a European supplier (Baader or TS-optics) for about 30 euros, but I can't find it now.

In the end I upgraded to a Canon 450D because it would give me the temperature of the exposure too.  Total cost:

StarPal OAG, AliExpress: £60-ish

QHY 5L-ii mono cam, AliExpress: £100-ish

Canon 450d, Ebay: £80-ish

C-CS adaptor for OAG: £5 (it needs an extra few mm and then reaches focus without any fiddling).

BTW the focus point for Canon and Nikon are about 2mm different.  You'll need the spacer, which I think is provided, or maybe the low-profile t-ring is thicker.

The only thing I would say is that I get a lot of fixed pattern noise from the Canon and if I'd had the cash I might have used the ZWO ASI 290 mm-s, it seems to be a lot more sensitive.

Hope that helps, 

Steve.

 

Thanks for that Steve. That adapter could do the trick with OAG replacing the t ring is it.  
 

So Low profile adapter into OAG straight into MPCC. 
 

With the OAG I see lots are purchased with a helical focused which seems to be where this conversation has headed is that correct. 
 

Thanks for your help everyone. 

[SteveBz]

3 hours ago, Kiwi_Brad said:

So Low profile adapter into OAG straight into MPCC. 

That's right. The StarPal OAG is manufactured specifically for the MPCCIII, but as you notice, not for Nikon.

If I could get a low profile focuser for the Guidecam of depth 10mm, I'd do it, but the lowest I can find is 17mm. Otherwise I'll just play with the focusing screws.

The OAG journey has been quite hard and it exposed other weaknesses in my setup, such as the Dec backlash on my mount - queue DIY belt upgrade. But I have now started to dither and drizzle, which I'm quite pleased with. So all together, lockdown has provided the opportunity to really up my game.

Good luck and clear skies.

Steve.

Edited December 29, 2020 by SteveBz

[Kiwi_Brad]

On 29/12/2020 at 22:29, SteveBz said:

That's right. The StarPal OAG is manufactured specifically for the MPCCIII, but as you notice, not for Nikon.

If I could get a low profile focuser for the Guidecam of depth 10mm, I'd do it, but the lowest I can find is 17mm. Otherwise I'll just play with the focusing screws.

The OAG journey has been quite hard and it exposed other weaknesses in my setup, such as the Dec backlash on my mount - queue DIY belt upgrade. But I have now started to dither and drizzle, which I'm quite pleased with. So all together, lockdown has provided the opportunity to really up my game.

Good luck and clear skies.

Steve.

Thanks Steve appreciate the help and feed back. Possibly but worth the OAG journey just yet then. 
 

Brad