6 replies to this topic

[mattyg291]

Hello all,

 

So, basically, as the title states, I want to know if I can attach my Sony a600 to my Celestron Nexstar 8se for future lunar imaging - and even if it's a good idea. I have a T-adapter (and a couple other little things but I don't know the name and I am typing in bed), not sure if it's helpful or necessary.

 

Any comments/suggestions are appreciated!

 

Thanks.

[Wildetelescope]

Moving to Major and Minor Planetary imaging forum for a better fit.

 

JMD

[Borodog]

MMPI is the wrong forum. Should be LOI.

 

To answer the question, yes, you can attach an a6000 to a C8, and yes, it is a good idea. I would definitely recommend you get an f/6.3 reducer/corrector. Without it the Moon will not fit on the chip, and you will definitely see coma. The R/C will not flatten the field, but you will not notice the field curvature, particularly if you use intermediate focus between the center and limb, and it will perfectly correct the coma.

 

You will want to get the backspacing approximately right, which is by spec 105mm from the rear threads of the R/C to the sensor, although it needn't be perfect. As long as you're in the zone it's pretty forgiving.

 

The a6000 has a mechanical shutter; you will want to use a remote release or the 2s delay setting. Be sure to set your focus using the Focus Magnifier on the highest magnification. I focus on a nearby star with a Bahtinov mask, but you can focus on the Moon itself as well. Use Daylight white balance. Use ISO100, exposure will be something in the range of 1/125s, adjust as necessary to get the histogram bright without blowing out the highlights.

 

You'll get your best results from stacking multiple frames with Autostakkert. I typically capture dozens to a hundred individual frames (I have captured up to 250 frames in the past but it's tedious with the a6000). Capture in RAW and use RawTherapee to convert the frames to 16bit tif or png for stacking in Autostakkert. Do NOT capture in jpeg or video mode if you want the best results. Do not shoot high speed continuous (burst) mode. The shutter slap from the mechanical shutter will spoil all but the first frame of any burst (you could consider cranking the ISO up to 800 or 1000 and dropping the exposure commensurately to freeze the vibration, but the shot noise per frame goes way up and you would need many more frames to get the same noise level). 

 

Here's some of my lunar images with an a6000 and a reduced C8*:

 

https://www.cloudyni...rees-elevation/

https://www.cloudyni...olor-corrected/

https://www.cloudyni...160-earthshine/

https://www.cloudyni...ass-transit-ii/

https://www.cloudyni...craft-transits/

https://www.cloudyni...on-of-hd-17996/

https://www.cloudyni...-by-earthshine/

https://www.cloudyni...-the-full-moon/

https://www.cloudyni...7-a-wider-view/

 

*Technically some of these were shot with my 10" Dobsonian, but the focal length is almost identical to the reduced C8, so the shot would be very similar either way.

[mattyg291]

MMPI is the wrong forum. Should be LOI.

 

To answer the question, yes, you can attach an a6000 to a C8, and yes, it is a good idea. I would definitely recommend you get an f/6.3 reducer/corrector. Without it the Moon will not fit on the chip, and you will definitely see coma. The R/C will not flatten the field, but you will not notice the field curvature, particularly if you use intermediate focus between the center and limb, and it will perfectly correct the coma.

 

You will want to get the backspacing approximately right, which is by spec 105mm from the rear threads of the R/C to the sensor, although it needn't be perfect. As long as you're in the zone it's pretty forgiving.

 

The a6000 has a mechanical shutter; you will want to use a remote release or the 2s delay setting. Be sure to set your focus using the Focus Magnifier on the highest magnification. I focus on a nearby star with a Bahtinov mask, but you can focus on the Moon itself as well. Use Daylight white balance. Use ISO100, exposure will be something in the range of 1/125s, adjust as necessary to get the histogram bright without blowing out the highlights.

 

You'll get your best results from stacking multiple frames with Autostakkert. I typically capture dozens to a hundred individual frames (I have captured up to 250 frames in the past but it's tedious with the a6000). Capture in RAW and use RawTherapee to convert the frames to 16bit tif or png for stacking in Autostakkert. Do NOT capture in jpeg or video mode if you want the best results. Do not shoot high speed continuous (burst) mode. The shutter slap from the mechanical shutter will spoil all but the first frame of any burst (you could consider cranking the ISO up to 800 or 1000 and dropping the exposure commensurately to freeze the vibration, but the shot noise per frame goes way up and you would need many more frames to get the same noise level). 

 

Here's some of my lunar images with an a6000 and a reduced C8*:

 

https://www.cloudyni...rees-elevation/

https://www.cloudyni...olor-corrected/

https://www.cloudyni...160-earthshine/

https://www.cloudyni...ass-transit-ii/

https://www.cloudyni...craft-transits/

https://www.cloudyni...on-of-hd-17996/

https://www.cloudyni...-by-earthshine/

https://www.cloudyni...-the-full-moon/

https://www.cloudyni...7-a-wider-view/

 

*Technically some of these were shot with my 10" Dobsonian, but the focal length is almost identical to the reduced C8, so the shot would be very similar either way.

Great info, thank you! Could you give me tips on actual attachment as well? I am messing around with the R/C and the camera and am not really sure how it should all fit. It doesn't seem like I can just attach the sensor to it, meaning no lens, but I can't seem to get anything to screw into place. I have tried a t-adapter and an M42-42 adapter.

 

I am guessing I will need another adapter just not really sure which one.

[Borodog]

Basically the reducer/corrector has what are called "SCT" threads. The Sony a6000 uses the E-mount attachment system and has a flange focal distance of 18mm. So whatever you use to connect needs to go from SCT threads to Sony E-Mount and add 105mm - 18mm = 87mm of spacing.

 

I presume your t adapter is E-mount. What size threads does it have on the telescope side?

[mattyg291]

Basically the reducer/corrector has what are called "SCT" threads. The Sony a6000 uses the E-mount attachment system and has a flange focal distance of 18mm. So whatever you use to connect needs to go from SCT threads to Sony E-Mount and add 105mm - 18mm = 87mm of spacing.

 

I presume your t adapter is E-mount. What size threads does it have on the telescope side?

If I remember correctly, I used to have it in this order: telescope, reducer, t-adapter, m42 adapter, and then whatever camera I was using at the time. So, on the telescope side, I had the reducer attached (at least I believe I did). I did some research and couldn't find any real info but the adapter is a Celestron SC #93633-A if that helps with anything. 

 

I am also a newbie at this stuff, so my apologies if some things sound a little weird. 

[Borodog]

Ok. If your E-mount T-ring is 37mm, then that's all you need:

 

Telescope => f/6.3 reducer/corrector => #93633-A T-adapter (50mm) => Sony T2-NEX E-mount T-ring (37mm) => Sony a6000 (18mm) = 105mm.

 

If your E-mount T-ring is low profile, you may need an M42 extension tube to make up the length. Or just order the correct length E-mount T-ring. I have one exactly like the one I linked (I also have a low profile one for other applications).