ADC necessary?

[Ozone]

Is an ADC necessary when using a Maksutov ( I have a Orion 150mm) or Schmidt? I think this may be the problem I've been having here in Ohio... After doing extensive tests with different camera settings (ASI224MC) and firecapture, I have all but given up. My planetary images all seem to lack sharp detail. The moon doesn't look bad, but Jupiter and Saturn, all the bands seem to blend/smear together. I have checked collimation, and focus with a bahtinov.

[geoflewis]

What altitude was Jupiter when you were imaging it, I suspect pretty low down in which case an ADC will definitely help, especially when using a colour camera.

[Ozone]

Yeah it's definitely low. I'm just trying to figure out if something I'm doing wrong. I was able to get more detail with my unmodified Canon t2i and 6" reflector. I've had the camera since Xmas 2017, the mak since Xmas 2018. I never have gotten a good image yet with the asi. I read they were alot more sensitive then the standard cameras. I have kept the histogram pretty even in firecapture, so I'm not sure what I'm doing wrong (they have been getting better. This is from my reflector and t2i and a 8-24 zoom at 640x640 which is 60fps. This was taken in January of 2014.

Edited August 27, 2019 by Ozone
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[Ozone]

I take part of this back. I have some good images of the moon from December 26 last year with the asi. I don't think I had the mak yet as it was ordered on the 17th.

[geoflewis]

Jupiter’s altitude in Jan 2014 was much more favourable than it is currently and that is a lovely image. Both Saturn and Jupiter are at the bottom (most southerly) of their cycles and very challenging from northern latitudes, so much so that I have only taken a couple of runs at them in 2019 (in fact I think only one run at Saturn) and that’s even using an ADC with mono ASI120. I think your recent Jupiter is pretty typical for its current low altitude. They have both started to head north again, so things will improve, Jupiter more quickly than Saturn. If you’re getting good lunar images then that shows the potential of the camera, but my advice would definitely be to get an ADC if you are going to continue imaging with s colour camera.

Good luck, Geof

[Ozone]

Thanks. Like I said, I'm pretty sure (90%) that the good images of the moon were taken with the 6" reflector, not the mak. That was my main reason for asking about the adc. Even images of the moon with the current set up, are lousy. Seems to me that with the different focal length etc. That the mak is alot more sensitive.

[CraigT82]

The jupiter image in your original post doesnt show any dispersion so I'm not sure am ADC will help you. Have you checked the collimation of the mak? 

[Ozone]

Good point. Not recently. Check that tonight.

[Ozone]

Can a chesire or collimation cap be used on a mak?

[Stub Mandrel]

You are about 10-12 degrees south of where I am, so the need for an ADC isn't as pressing. I suspect that you would gain more by using a barlow. I use a 1200mm focal length scope with a x3 barlow element.

If you were in the UK I would say definitely get an ADC, but in mid Ohio Jupiter should  be getting up to about 27 degrees where the benefit will be marginal.

Results are very dependent on the quality of seeing and can be very different on different nights.

If you use Sharpcap it's worth spending a while carefully focusing using the focus assistant or a nearby star (Antares should be well placed for you) with a bahtinov mask.

[John]

1 hour ago, Ozone said:

Can a chesire or collimation cap be used on a mak?

A simple star test will show you if the collimation is good or not. With the mak-cassegains I think the star test is also a good method to use while adjusting the collimation as well.

 

[Ozone]

As far as focus I do use a bahtinov. I will try sharpcap. I always use firecapture. I will have to do the star test, I don't have anywhere far enough to use an artificial one. I have a 2" collimation cap, everything looked good there, but nothing beats a star test. 

[geoflewis]

Just another thought, are you allowing your Mak to cool for a couple of hours or more before using it for planetary imaging? The OTA needs to be at the same temperature as the ambient air outside or air currents inside the OTA will ruin your images.

Geof

[Ozone]

Yes. I started at dark. Put everything away about 1-2 am. If it wasn't equalized by that time, I don't think it ever will.🤗

[Ibbo!]

I think no matter what we do at the moment in Uk type latitudes we are going to have to accept poor Jupiter and Saturn images until they gain a decent alitude.

Making sure the kit has cooled, collimation, focus, ADC and seeing are all good things to check but until we are not looking thorough the bulk of our atmossphere we will have to tough it out.

I have given up with Jupiter and Saturn for this year now as they are very close to my garage if not in it .

That does not mean ther will be no more images unleashed on the poor unsuspecting viewers of this forum as there is a load of data I have not stacked yet - you have been warned.

Or go south.

[Stub Mandrel]

I took an afocal shot through my dob, which was awful, but the dispersion was about 1/8 of the size of the disc, so unless you are imaging it about 8 pixels high an ADC will improve the results!