DSLR Settings in warmer weather?

[pfitzgerald (Paul)]

Hi Folks

This is my first full summer trying to image DSOs with a DSLR. Most times I am shooting 5 to 7 minute guided subs at ISO 800 but have noticed a significant increase in noise (and LP) creaping into my images. I can't do anything yet about the LP as I don't have a filter - mini question - are they really worth purchasing?

My main question is: Should I be trying a lower ISO setting eg 640 or 400 for these length exposures, or higher ISOs coupled with shorter exposures? Is there a definitive answer, or is it a matter of experimenting to see what works and then try to reproduce better results on successive nights?

The DSLR I'm using is the Canon 60Da.

Tonight looks like it will be cooler than the last few nights and everything is set up and ready to go, but with work tomorrow I can't afford to pull an all nighter - probably 1AM at the absolute latest.

My target for tonight is NGC 2244, The Rosette Nebula if that helps with your advice.

T.YA.I.A.

Paul

[BlackWidow (Mardy)]

Yes a CLS filter will help, I use on an it has been one of my best purchases. Difficult when it's really hot as the longer you camera is on the worse the noise will be. You have to play around to get the best setting. Going to a really high ISO . will give you noise no matter what. I would be shooting at around 400 to 800 dependent on your scope f: ratio. Make sure you use the LCD display as little as poss as this will increase the operation tems of the camera.


Mardy

[Rod771 (Rod)]

If you have LP definitely get a filter , Astronomik CLS CCD will work great. I wouldn't go over ISO 800 it seems to be the sweet spot for the 60da.

You have it right though, its all about experimentation.

[cometcatcher (Kevin)]

How warm are we talking? Once the temps get into the mid to high 20's, the best setting is the "off" position. DSLR's go totally noisy at high temps. Otherwise the early hours of the morning will be cooler.

[pfitzgerald (Paul)]

Thanks Mardy/Rod

The scope is an F\7.5, but with the focal reducer is F\6.3.

Experiment it is then, and save the bickies for an LP filter. I take it that it's a clip in filter for the camera? Once I have said filter do I need to change exposure lengths or ISO settings, or is status quo?

Paul

[pfitzgerald (Paul)]

Hi Kevin

High 20's, although the other night I think that it was still about 30oC at midnight.

It wasn't until about 2:00am that the noise level in the images dropped significantly. I'm tempted to construct a dry ice cold box to cool the camera down.

Paul

[traveller (Bo)]

Paul, I have a cls clip in filter for my 40d, so if you want to borrow it one weekend just let me know.
Cheers,
Bo

[cometcatcher (Kevin)]

Yeah it's frustrating, especially revisiting objects that were imaged in winter only to find the mass of noise in summer. For myself I find I have to stick to the bright stuff in summer and leave the faint objects for cooler weather.

I also found a CLS filter to make things worse in some cases when at 30C. The reason was the higher ISO / longer subs needed for the CLS overran the image with noise. But then I was using a Pentax K-x which totally dies in the heat.

[MrB (Simon)]

Hi Paul.
I had planed to follow Roger Clark's lead and do the following for the 60Da, tho I've never found the time. I'll get there eventually but thought you might like to have a read and possibly give it a go yourself:
http://www.clarkvision.com/astro/can...gnal-to-noise/

Lots of other interesting reading on that site too.

Edit: note that the LCD obviously has less heating effect on the 60Da as it does on other bodies, however prolonged use of live view does increase the sensor temperature, whether you use the LCD or remotely via a PC, so try to use live view sparingly and briefly.

[pfitzgerald (Paul)]

Thanks for all the input Guys

Scope and camera are set up to six minute subs at ISO 800 for the next two hours. Ten minute exposures and it was almost polar bear in a snowstorm material with the histogram about 3/4 of the way out to the right. The settings I've settled on have the histogram about halfway. None of the other ISO settings (640-400) seemed much better, they were 'darker' but even with longer exposures didn't appear to enough data.

Anyway, if anyone is interested let me know and I'll post the final results.

Paul

[Chris85 (Chris)]

Hi mate I feel your pain. The last few times I've been imaging I'd have the camera running at iso 200! Any more and it was just pointless. BackyardEOS had my sensor temp running in the mid 40s :-(
As I understand there's exactly the same amount of photons hitting the chip, regardless of the iso, so I just take a few more subs and just stretch the stacked result a bit more than usual.
Cheers

[blink138 (Pat)]

hi paul i too have the 60da and it is the first camera of any sort i have ever had
i have noticed in some of my "warmer" pics they pick up striations running through the whole frame
rod is correct i shoot everything at iso800 because through trial and error this seems to be the best
i shoot prime focus through a c11 at f6.3 and my maximum exposure length is 3 mins with a 2" LP filter attached 5km from perth cbd
some people in severe LP cities still do not use an LP filter as they say it strips colour
there is a man that lives only a few k's from me here who does not use a filter and he has some of the best (especially wide field) pics i have seen so there must be some validity to this argument
good luck
pat

[kosh]

Definitely interested in your results Paul.
I have had a issue of an orange streetlight which with the newt, just peeks over the fence and provides a beautiful bit of light pollution when trying to image the flame-horsehead region after about 11:30pm anything away from that direction is actually ok, but I am screaming out for an LP filter too.

Hope your session turns out well.

[skysurfer]

It seems that with hot weather it is *better* to use high ISO and shorter exposures. Long exposures in hot weather do fog earlier with noise I have heard.
I recently used ISO 1600 subs with my 40d (each 30 seconds) while in Bali (about 25 C) and after stacking with DSS with only 6-12 frames I got nice images.
Now I have a 6d so I can add an extra 2 stops but I yet have to test it in hot weather next month in South Africa. Here in Holland it is winter now.

[rcheshire (Rowland)]

This subject is more complex than temperature related. But iso800 is a good compromise in my experience.

Cameras have different properties. The 1000D is unique, besides being 12 bit, in that the sensor temperature flat lines once it is operating. The 40D is similar but slightly warmer. The 5D MKII is a hideous thermal monster and I prefer the older style 14bit camera. It would be interesting to make comparisons of newer camera models and sensor heating.

I sold my CLS-CCD filter because it was more trouble than it was worth. Unmodded cameras may benefit, but careful selection of iso and exposure times is just as effective, I think.

[kosh]

Originally Posted by rcheshire

This subject is more complex than temperature related. But iso800 is a good compromise in my experience.

Cameras have different properties. The 1000D is unique, besides being 12 bit, in that the sensor temperature flat lines once it is operating. The 40D is similar but slightly warmer. The 5D MKII is a hideous thermal monster and I prefer the older style 14bit camera. It would be interesting to make comparisons of newer camera models and sensor heating.

I sold my CLS-CCD filter because it was more trouble than it was worth. Unmodded cameras may benefit, but careful selection of iso and exposure times is just as effective, I think.

I just received a 1000D that I bought used from ebay for the purpose of self-modding it. I was planning to get some sort of ir-LP filter for it. What kind of issues did the filter give you Rowland?

[rcheshire (Rowland)]

Hi Goran. I have done 3 conversions so far and the easiest was to remove both factory fitted filters (1000D) and use an Astronomik IR/UV clip in filter from BINTEL. I have tested autofocus and it works.

Previous conversions were to a 1000D and 5D MKII using Astrodon inside filters. You need dust free conditions. It's fiddly and in hindsight unecessary - might get a few arguments on that one.

Some conversions refit the low pass front filter, which is an antialiasing device. My observations are that images are sharper - you don't need it, whether you go for an inside or clip-in filter.

Follow the Gary Honis instructions for disassembly and reassembly, and you should be OK.

The 1000D is a hardy little camera. I have subjected 2 to several cooling conversions and they just keep working.

[kosh]

Thanks Rowland.
I have watched Gary's videos and also his guide on the website so hopefully I will go ok. I was planning a clip in uv/ir from bintel as you suggested so I can't wait to get it done and try it out. I really hope the increased sensitivity will allow me to get some better detail around IC434.
Unfortunately this new moon I'm moving house so it will all have to wait a while

[kinetic (Steve)]

Paul,

Justin did some great background research on this you might like to glance over.

The thread is here.

Steve

[pfitzgerald (Paul)]

Thanks for that Steve, I'll have a read over it when I've done my 'homework'.

Paul