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Help with a used camera purchase decision

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#1 macbates

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Posted 19 November 2019 - 09:27 PM

I’m looking into acquiring a used Canon camera for astro work, and wanted to see if I could get some opinions (usually no problem there, of course). Right now I’m using both a Canon 7D2 and a Canon 5D4 with a ZS-61 on a CEM-40. I would like to use an astro modded camera, but definitely don’t want to modify either of these two since they’re both in use for ‘normal’ daytime shooting (of which I do a lot). Given the investment I have in Canon infrastructure, I want to stay with Canon, so I’ve been looking into the Rebel lineup.

 

I’ve been browsing keh.com for used cameras, and the prices seem reasonable. I know a lot of folks use the T3i and like it, and KEH also has a full range of used ones from the T3i up to the T7i (with increasing prices, of course). From what I can see, as you move up the line from a T3i to a T7i, very few of the functionality increases relate to astro work. The newer ones probably have better noise reduction, but other than that it seems to me that there’s not a large advantage between a T3i and a T7i when it comes to pure astro work.

 

Any thoughts on this? Specifically, are there good reasons for going to a T4i (or T5i-T7i) instead of a T3i when it will be modded and used strictly for astro work? Any and all thought on this would be more than welcome, and thanks in advance.

 

 - Ken



#2 GalaxyPiper

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Posted 19 November 2019 - 11:11 PM

Canon does not make the T3i anymore, so if you mod it, just like any mod, you would be taking the responsibility to repair any damage or un-modding the camera.

I have a Canon 60D and a Canon 60Da. The Da of course is the Astronomy camera that the company promoted for that use only. It will work just like a normal Canon 60D if I install a filter in it that cuts down the hydrogen- alpha band. Most Canon camera's I would imagine would work the same way if modded. Just add the filter, and then no problems, just like it had not been modded at all.

Canon does not make the 60Da anymore either, and the 20Da is also Canon's first foray into the Astronomy realm.

It's like any hacks, you take the responsibility by doing it yourself, or have someone do it for you. The only thing you have to consider is the sensor size, and of course how much you want to spend.

Time or Money.

 

Here are some comparisons:

 

https://astrobackyard.com/canon-60da/


Edited by GalaxyPiper, 19 November 2019 - 11:15 PM.


#3 Jerry Lodriguss

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Posted 20 November 2019 - 07:03 PM

I’m looking into acquiring a used Canon camera for astro work, and wanted to see if I could get some opinions (usually no problem there, of course). Right now I’m using both a Canon 7D2 and a Canon 5D4 with a ZS-61 on a CEM-40. I would like to use an astro modded camera, but definitely don’t want to modify either of these two since they’re both in use for ‘normal’ daytime shooting (of which I do a lot). Given the investment I have in Canon infrastructure, I want to stay with Canon, so I’ve been looking into the Rebel lineup.

 

I’ve been browsing keh.com for used cameras, and the prices seem reasonable. I know a lot of folks use the T3i and like it, and KEH also has a full range of used ones from the T3i up to the T7i (with increasing prices, of course). From what I can see, as you move up the line from a T3i to a T7i, very few of the functionality increases relate to astro work. The newer ones probably have better noise reduction, but other than that it seems to me that there’s not a large advantage between a T3i and a T7i when it comes to pure astro work.

 

Any thoughts on this? Specifically, are there good reasons for going to a T4i (or T5i-T7i) instead of a T3i when it will be modded and used strictly for astro work? Any and all thought on this would be more than welcome, and thanks in advance.

Hi Ken,

 

Try what you have, unmodded, for astro work. For red emission nebulae, a light-pollution filter will really help. What you have should work great. Unless you want really faint red emission nebulae, then you would want a modded camera. But if you are willing to put in the extra exposure time (like 3x more total), you can get good results with an unmodded camera. 

 

As you go up from the T3i, every new generation of sensor/processor is going to improve the signal-to-noise incrementally.

 

S/N is everything. But you can always make up for an older camera with poorer s/n by using more total exposure to increase the signal to overcome the noise.

 

Whether a T7i is better than a T6i is better than a T5i is better than a T4i, is better than a T3i?  Yes. Incrementally.

 

How much?  How much is your time worth compared to the cost of the camera?

 

Let's say, just for arguments sake, Camera 1 is twice as good as camera 2. But camera 1 costs twice as much.

 

But, you can take a good pic in one hour with camera 1 whereas you need 2 hours for camera 2.

 

So it comes down to what you can afford. Your time or your money. If you shoot really faint stuff, it doesn't take long for the mod cost to pay for itself.

 

Here's an shot of some faint stuff: It's 300 minutes at f/2.8 from mag 20.67 skies with an unmodified Nikon D5300:

 

B33_M42_M78.jpg

 

Jerry


Edited by Jerry Lodriguss, 20 November 2019 - 07:12 PM.

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#4 erictheastrojunkie

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Posted 20 November 2019 - 09:42 PM

The old Canon rebel cameras just pale in comparison to something like a modded D5300/5500 camera, you can find those modded D5300's for relatively cheap on the classifieds (usually sub-$500) so there's really no reason to go the old Canon route unless you're seriously strapped for cash. Fwiw (I know this isn't totally bueno on the forums) I'm going to be selling my D5300 in the near future to make way for a mono-cam, I modified it myself and have been getting some pretty **** good shots with the L-pro and L-eNhance Optolong filters over the last year or so. If you're at all interested you can DM me about it, I'll be selling the filters as well. I can say, from using an old modded 550d to a modified D7000 and now a modified D5300, the Nikon is just so much better and worth the extra couple hundred you'll pay.

Sent from my Pixel 2 XL using Tapatalk

#5 Dwight J

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Posted 20 November 2019 - 10:05 PM

I bought a modified T3i here.  He found me a used body ( 4000 actuations) and fully modified it for $520 Cdn.  I think his price may have gone up but the exchange should make this a great deal for US customers.

https://www.astrobuy....php?view=49965



#6 macbates

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Posted 21 November 2019 - 09:40 AM

Jerry:

 

Thanks very much for the detailed comments; they're very helpful. I did purchase a CLS filter, but (naturally) it's been too cloudy the past week to use it. Hopefully I can try it this weekend and see what kind of a difference it makes. I'll also hold off a bit on any other purchases until I see what longer exposures can do for bringing out more details. Thanks again for the help.

 

Dwight_J: Thanks for the pointer; this looks like a good way to get an astro modded camera for a reasonable price.

 

 - Ken



#7 asanmax

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Posted 22 November 2019 - 11:27 AM

I've tried some Canon cameras and found that two models, Xsi (450D) and T3i (600D) are less noisy. T3i is a bit better than Xsi. Both models give amazing results if you have them at least Ha modified, the sensitivity in Ha and OIII increases and you can catch a lot more faint details in emission nebula. Your CLS filter will help you a lot if you shoot from a light polluted place.

Please have a look at my comparison here https://www.cloudyni...lter-for-canon/



#8 the Elf

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Posted 23 November 2019 - 04:58 AM

I'm using an unmodded T3i and a mono mod. I have the great opportunity to work in an optic lab so I could measure the T3i's spectral response. Even unmodded a reasonable bit of Ha comes through.

 

600D_spectr_sens.JPG

 

This was the first test run of our monochromator, not inplemented in the lab software, so I had to type in the readings to an excel sheet..... The plot is just normated, setting the maximum to 1. This is not a QE measurement. The Ha sentivity is about 25% of the maximum sensitvity of green. That's quite a high level. A mod will lift it a bit higher but not much. You will stay under the red maximum for sure which is about 1/2 of the green. In photographic terms this is less than one f-stop! If you have/get the book Digital SLR Astrophotography by M. A. Covington you find a comparison of a modded and unmodded DSLR on the cover. He says it is not worth it for the little bit of signal. OTOH: if you can get one for a good price it won't harm either!

Here is an example shot with the unmodded T3i:

http://www.elf-of-lo...C_only_demo.jpg

You will be limited to the strong Ha objects with a DSLR, modded or not. Do this for a while and when you want to get deeper into the rabbit hole think about a cooled mono astro camera or a mono mod (hard to find and expensive or the most challenging DIY you can think of).

 

I recommend you do not even think about using a modded camera for daylight. Most functions that you love for daylight are irrelevant for astro. If you can get a modded camera for a reasonable price, do so. Check what was done: if the filter is just removed and not replaced by some other glass the camera will work fine on a telescope but a Canon lens will no longer come to focus. If all filters have been removed you might need a clear UV/IR blocker for imaging. Even if the glass was replaces and even if you find a filter to make it work in daylight the autofocus only works if it has been re-adjusted after the mod. You do not need many megapixels. The larger the pixels the better. I'm happy with my T3i but from what I read hear all Nikon users are conviced Nikon is far better for astro. Alas there are no side by side comparisons of the two. All posts are lacking data for the amount of dark current. Now that I have the Canon's I wont swap to Nikon. When you are still in the decision phase you might want to collect some information about Nikons as well.

 

@Jerry: would you call horse head and orion faint? I think they are bright targets, bright enough for DSLR imaging. The point is using a lens with f/2.8 gives you a lot of detail in a short time while a regular small refractor at f/8 or slower won't.


Edited by the Elf, 23 November 2019 - 05:17 AM.


#9 SandyHouTex

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Posted 23 November 2019 - 11:23 AM

I’m looking into acquiring a used Canon camera for astro work, and wanted to see if I could get some opinions (usually no problem there, of course). Right now I’m using both a Canon 7D2 and a Canon 5D4 with a ZS-61 on a CEM-40. I would like to use an astro modded camera, but definitely don’t want to modify either of these two since they’re both in use for ‘normal’ daytime shooting (of which I do a lot). Given the investment I have in Canon infrastructure, I want to stay with Canon, so I’ve been looking into the Rebel lineup.

 

I’ve been browsing keh.com for used cameras, and the prices seem reasonable. I know a lot of folks use the T3i and like it, and KEH also has a full range of used ones from the T3i up to the T7i (with increasing prices, of course). From what I can see, as you move up the line from a T3i to a T7i, very few of the functionality increases relate to astro work. The newer ones probably have better noise reduction, but other than that it seems to me that there’s not a large advantage between a T3i and a T7i when it comes to pure astro work.

 

Any thoughts on this? Specifically, are there good reasons for going to a T4i (or T5i-T7i) instead of a T3i when it will be modded and used strictly for astro work? Any and all thought on this would be more than welcome, and thanks in advance.

 

 - Ken

The T7i has a new lower noise sensor, which would be a benefit.



#10 the Elf

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Posted 23 November 2019 - 02:08 PM

Sandy,

 

can you offer some measurements or source where that information comes from? Especially how much dark current in e- per second per pixel at what temperature it has got and how it compares to the T3i for example. People keep on refering to read noise which does not count much on long exposures. It is the dark current that counts and how it goes with temperature. Thank you!




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